I think of the 5th house as relating to pleasure and the 8th as relating to intimacy as far as I understand it right now.
For me these are sort of difficult areas of my life.

I have 5th ruler opposed by jupiter , squared by vertex, and chiron -I tend to not fully enjoy/take pleasure in the moment as I should. I get too wrapped up in meanings and responsibilities and the pleasures/happiness of others.

and 8th ruler opposed by sun and squaring ascendant/descendant. - I have issues with domination/power/control and trust in relationships. I fear control and refuse to be dominated (even if part of me wants to find that person I can trust and give into with pluto in the 5th-libra...no one has proven trustworthy yet and I can't let go until someone does)

It would be interesting to look at your entire chart to see how your chart rulers are aspected and how they fit in the bigger picture.
Here is what came to mind just from what you mentioned (It won't give a complete picture without the whole chart but I will try):

cancer 5th house and moon in 10th capricorn....makes me think of traditional mother-father roles...but I don't know what more to say than that (the 5th house also deals with children) For some reason those seem to mesh into caring for/providing for children to me along with a home.

scorpio 8th and pluto in 7th libra/ mars in 6th virgo...
with uranus in 8th scorpio
I, too have that scorpio uranus. It probably provides a whole lot of excitement but possibly some instability in the area of intimacy. Does mars aspect uranus? This sounds sort of rebellious and independent to me on at least some level or other. There seems to be something unusual here.

I could be totally wrong! I also don't want to say too much...
If you post your chart people can give you more details and see the whole picture better. I probably wouldn't say anything more than that where everyone could read it, though -I'm trying to get better about that lol.

I think of the 5th House as courtship, and the 8th House as the underlying psychosexual emotional dynamics which truly cement a relationship. The 8th House really shows the "give & take", while the 5th House just shows what type of activities you are likely to engage in in the early stages of a relationship.

In my case, my 5th House cusp is at 27* Aries. It is usually a sense of competition and a challenge or achase which gets me going. Also, outdoor activities and highly physical play and resetlessness get me going as well. However, once I am there I need something much more serious and soul-oriented to keep me there...and that is significated by havin Cancer on the 8th. I need sharing of emotions and weaknesses. My Moon is in Scorpio in the 11th, and this gives an idea of the overall quality of my "give & take" and sharing of emotions. I need my lover to absolutely be my friend also and to take part in my hobbies and associations somewhat. Luckily my girlfriend is well-learned on the topic of astrology even though she's not into it like I am. In the case of my 5th House which is ruled by Mars through Aries, my Mars is IN Aries and conjunct the house cusp itself. I have a special connection between my 8th and 5th houses, because the Moon rules my 8th and Moon is in Scorpio which is ruled by Mars....and my Mars is in Aries in the 5th as I said. Mars is the final dispositor because Mars rules Aries, so boisterous competetive play and perpetual courtship usually is the medium by which I remain interested in a relationship. I've learned to tone it down over the years though! ;-)

Now the real mystery is my girlfriend, who has her 5th ruled by Venus (Libra) and her Venus is in Taurus in the 12th House. Her 8th House is ruled by Capricorn and Saturn, and her Saturn is in Taurus in the 12th. She is rather inhibited, stoic and slow until things are just right, and she needs to be coaxed to loosen up and relax. The 12th House makes her prefer to keep her affections very private and hidden from public view, and especially from people who know her but are not involved with her romantically. For this reason, she likes the anonymity of a hotel or parking a car in the middle of nowhere. I think maybe in a past life she was a person with such overwhelming responsibility that she had to keep her love-life absolutely concealed and private. Maybe she was a nun. ;-)

Now in your case, Katey...it sounds like you court your lover by showing or expecting passive and subtle sensitivity, and with the Moon in the 10th you want your lover to be sensitive to your highest goals and take them seriously...or perhaps you want someone who takes their own goals and success very seriously...a tenacious person perhaps, ho works steadily towards what they want. Once you are satisfied these qualties are in place, and that your partner is sensitive to these qualities, then you move forward.
With Scorpio on the 8th, and Mars and Pluto in houses 7 and 6 respectively...I believe it means that marriage and commitment are extremely important to you but you may be overly idealistic, and perhaps you fuss over the details of your partner's personality or their habits. Perhaps you try to change them or they try to change you.

I have been searching around on this and have found the following key words for 5th and 8th
5th - Creativity Children Risk taking
8th - Intimacy Sexual nature Financial Legacy
But it seems that for realtionships 7th is more significant?
7th - Marriage Significant Other Partnerships
Any Insight much appreciated and thanks for everything already written.

The 5th and 8th house do say something about the types of romantic relationships and persons we attract. Sometimes it can be clear-cut but sometimes it takes more than what the house's sign says. I'll use mine as an example.. My 5th house is in the sign of capricorn. I have never been involved in capricorns or guys who embody the capricorn qualities. I am definitely not into authoritative, worldly, ambitious types. However, the ruler saturn( maturity) is in the 12th house, and I've always admired someone who has a different kind of maturity. I look for spiritual/mystical(12th house) rather than a more practical, earthy type of maturity for me to connect to them.
My 8th house is in aries, with my mars in cancer in the 11th house. I have never been involved with any cancer or any aquarian types. I'm very much drawn to scorpios though but that's because of my venus in the 8th house and 2 other planets. Having said that, I don't get obsessed with only scorpio guys.
The most interesting thing I discovered about the types I had been so crazy attached to, was not the sign of the 5th and 8th house and the position of the ruling planets in the chart but how their venuses activate my planet in synastry, more specifically, my uranus. The one constant thing I get is when their venus creates a hard aspect to my uranus. Conjunction, square, opposition.. you name it, I had that with all the guys I was interested in. The ones that did not, well, let's just say I couldn't get into them. It's like I'm looking for that erratic quality in my relationships. Of course they never really last or some of them wasn't really what I would call a real relationship, but it felt so good while it lasts. So I guess look for the most constant pattern in your synastry and you will uncover the type of partner you're drawn to. Good luck!

Wonder what it signifies when a person has only Chiron in the 8th house? And what if that person's Chiron falls in your 7th house where your own Chiron and Sun lie?

what an interesting discussion!
im not as advanced in astrology as you folks are...can you take a look at my chart (ill post a link below) and tell me what aspects (is that the term im looking for? trines, conjuncts etc) are goin on with my 5th and 8th houses and your interpretations and what the houses mean, in regards to this topic, the 5th and 8th houses in sexual relations?

you know like a "for dummies" or "cliffs notes" type explanation?

purty please? :)

thanks!
www.astro.com/cgi/chart.cgi

hope that link works...