Is a 20 year old guy to old for a mature 17 year old to hang out with or possibly date?

I would guess that your parents would be most concerned. That aside I don't think the age difference presents a problem.

It would be illegal for a 17 year old to date a 20 year old or otherwise be romantically involved. A 17 year old is STILL a minor by US law and a 20 year old is considered an adult - THAT is what makes it illegal. Do NOT automatically fall into the "age of consent" crap either. It IS NOT automatically a free pass. There ARE "loop holes". The Romeo and Juliet law only goes so far. A typical example of that is as follows - the age of consent in your area is 16. You are 16 and dating someone who is 19. By the Romeo and Juliet law, a minor that is of the age of consent may only date someone who is within 3 years older than them. This means your relationshi may be accepted as legal, because even though you ARE a minor with an adult, you are of "consent" and within the "proper age gap", so they would grant permission for it to go on. Now, if you were 16 and dating a 21 year old, no... it would NOT be accepted because the gap would be too far apart for a minor (unless the Romeo and Juliet law stated you could be up to years apart).

In your case, you're 17, You're VERY close to turning 18. I think the best thing to do would be talk as FRIENDS ONLY. Don't even try to kiss one another right now. Be friends and truly get to know one another. When you turn 18, if you're still talking, like one another and think you might want to try something more, then you are free to take it to the next level and begin something romantic.

Good luck!