Hey FB, great idea!
We've been married just over 12 years now ... went through a stage around 5 years where we really struggled & questioned our marriage, got counselling etc. This was before having kids - I'm so glad we got through that before we became parents. (we were both very interested in our careers and kind of drifted as we got absorbed). Since that time, life, love & marriage has just gotten better generally speaking (there are some rough spots but nothing like the crisis we went through @ 5 years).
One thing I think is key is both people beign able to identify what is important to them, and being able to work out a solution when things are in conflict. Usually if something is very important to one of us, it isn't a big deal to the other, or at least not so big a deal that it causes problems. Note that I believe there are some things where you both just must be on the same page - like kids or no kids, moving cities/job changes for one person, big money decisions ... I think those can be huge if both people aren't heading int he same direction. How to manage money has been an area of conflict for us at times, and at 12+ years we still haven't got it perfect ... but we are working on it together.
Let each other know the things you love, admire, get turned on by in him/her. One thing that came out of our 5 year crisis is we realized we'd stopped letting the other know these things, figuring that it must be obvious - I've learned that honest, sincere appreciation feels great to give & receive.
Laughter! I love it that I can make my DH roar with laughter when I tell a story about my day, or commenting on a subject we are interested in, or whatever. And he can crack me up too. Something about having a sense of humour like that really brings you together.
Supporting each other in interests taht are not in common, and having time to be on your own - that is really critical for me

Romance ... since we now have young children I've learned that little teasing, romantic, flirtatious moments are important. And creativity in intimacy is great too.
My parents have a great marriage and some of the thigns I've seen for them (and believe to be true of DH & I) is that both people have a good awareness of themselves, strengths, etc. and see the great things they bring to the relationship. There's a passage from "the Prophet" by Kahlil Gibran that says something like "the pillars of the temple stand not together, and the birch tree grows not in the oak's shadow." To me, it is important to be able to stand on your own 2 feet - to know that you could handle life on your own if you had to - and then enjoy having someone to handle it with. Being dependent & not having options seems to me a dangerous ground on which to build a marriage.
Cheers,
Andie