I can tell you about my crush. It should give you some thoughts and ideas that maybe you can draw from.
I had a serious crush on a guy. He was perfect in every way. His clothes was also perfect and clean and he was always clean shaven, nicely dressed and had this very sharp look to him. One semester he was in THREE out of four of my classes. Kinda hard to avoid him then. I kept looking at staring at him once in a while, while trying not to do that to not get him to notice. I desperately tried to find something wrong with him just so that I could get out of the crush as I was kinda stuck there with my thoughts and lack of action. It didn't work -- everything about him was perfect. I wanted him but was afraid of something. Perhaps of him not returning my feelings, or feeling of rejection in general. Another big reason was that I put him on a piedestal and idolized him. And I didn't talk to him because I was afraid that he would not pull up to being that idol I've made and hoped for him to be and that him being so high in my head, he just wouldn't give me the time of day or reject me.
I waited 2.5 semesters to talk to him. When I did talk to him it took me probably about 10 minutes to get the courage up and come up to him and talk. It was great and cool talking with him but it was non-eventful. He told me about his job, classes, etc. Talked about us being in 3 classes together.
My excuse to talk to him was the most ridiculous one, even that it was real. At my job (selling computer parts) someone with the same name as my crush happened to call and ask for an order. So I asked him if it was him. Can you think of a worser "pick-up" line ? "Ummm ... you see I work at so and so and yesterday a guy with this and this name called and asked for his order status. Was it you ? " he he but it worked as starter. I didn't want to talk about gay issues as I was afraid of rejection. That'd be really devastating if he'd reject it with all my build up of him. So my purpose of talking to him was to just feel him out. He didn't seem to pay much attention to him, and when his friend came up they talked for a while and I kinda felt ignored. Then his friend left and I think we exchanged a few more lines and then I left. I talked to him one or so more times when I showed him a magic trick. He didn't seem to be interested in me generally, so I generally stayed away as I do with most people due to my generally introverted personality. That's perhaps also the reason why I never invited him anywhere. I don't think it'd matter though, as my stance was that if he's interested things would have work out either way. That's a passive stance though -- when I have interest in someone, I seem to wait for their interest in general rather then trying to get interest from them
So soem time after that, I saw him a few more times, but after talking to him I didn't see interest back from him and my interest in him was not as strong... I felt as if it was his time to talk to me and he never did. I thought that he was perhaps straight though I held my fantasy of him being not so, or just being him without any sexuality label. I never saw him with girls. A few times with a friend for a short time, but he was mostly by himself.
I still had a hard time finding something wrong with him, but this time it was a little easier. There was nothing wrong with him physically in my head and there wasn't ! The only thing I could grab onto was that he was kinda aloof and not very engated when talking to me. That made him a bit less than perfect. Now I see it as he was just not interested in me. I figured that he was straight.
More to the story: I think 4 years or so later I wondered "what if" ? So I guessed and hoped he'd be on myspace and he was (!!) I found his profile where he's matured a bit and changed physically from what I remember him to be like in my thoughts. I wanted to see some pics of him younger, but there were none. oh well. He's still hot, but it was kinda sad to see him changed and ... being married to a girl.
--- extra thoughts.
In my case I tend to idealize things.
Had I not done that and rejection was not my fear, I'd probably talk to him on 1st/2nd day I realized I like him. Then I'd find out he's straight and just move on. Maybe become friends, or maybe not. Either way I'd probably be checking him out once in a while just cuz he was really hot, but then I would not have the feeling of a crush.
So what will you make it out to be, weeklyrentalbb ?
I chose to hang on to the fantasy and made the guy to be a perfect crush. He never had a clue, at least I don't think he did. Unless he saw me drooling over him during me talking to him, but I tried to maintain my composure
Another case. There was this HOT HOT guy I met recently who is also very hot.

I said to myself I won't be making a mistake of waiting that long. I talked to him very quickly. He was also by himself most of the time... I guess I feel safer to talk to people who are by themselves. I've seen him somewhere before. I realized it was at a meeting. He was hot. oh yeah. So I talked to him a couple of times, and he was more talkative and it was nice talking to him. His friend was there a bit further away, they talked, then we talked again. I don't know though. I couldn't pick up from him if he's gay or straight and I didn't want to ask. I guess I needed to spend more time on him and invite him somewhere and find out, but I didn't ... I have a boyfriend, but that was not an excuse though as why not make friends with him ? That again goes back to my introvertedness. I expect people to be interested in me, and I generally don't follow up on them if I don't feel they are actively interested back. I really need to change this. It may do me some good. Although I don't know if I can do this for a long term and thus I don't know how this issue of mine will affect the relationship in the end if I was to get the guy, he was gay, and we started having a relationship.
So in your case ... what do you want it to be ? This is "create your own adventure" part.
I say talk to him. This will be hard, and this may effectively put some dampers on the crush, but I think that ultimately knowing is better than guessing.