Sense of humor is a biggie for me - the guy has to be able to have a good laugh. I also wouldn't want someone who is always serious; my philosophy is to be serious when the occasion calls for it, and to try and have fun with everything else. I need someone whose not afraid to be silly or have fun.
Communication and honesty are also important. My ideal guy needs to be able to tell me what's bothering him, and I need him to be able to listen when I have somethig on my mind or listen to any other concerns (finances, marriage, etc.). And...he can't smoke, drink excessively or do drugs. All three are major turn-offs to me. Definitely has to like animals - my furbabies and I come as a package. And at least one shared interest is good. The last one, and it's quite big...it's a no-go if the guy wants kids. If he's the kind of guy who would be okay with kids and okay without, then I could probably work with that...but one who has his heart definitely set on spawning? No win.
Another thing...he can't be one of those ignorant guys who thinks that all women want to be treated to exensive fancy dinners and gaudy diamond jewelry - basically, he can't be of the mindset that women can be bought. No - my ideal date is staying home, playing video games over pizza and watching movies over hot chocolate. I don't like receiving gifts, and certainly not ones that cost hundreds of dollars. I'm more into old-fashioned romantics - guys who will stand outside your window playing 80s love songs out of a boom box and who will write you love poems, and give little gifts as signs of their love.
Picky? Yeah, I am. But my DBF meets most of my tastes (he couldn't do the boom box thing because my mom probably would have gone outside with the shotgun and told him off)...and, at the risk of sounding like a sappy teenager, I still feel as giddy around him now as I did when we first began dating - and it's been about three years. I love that man.