Most of the "guided" tours can be quite hectic - I've done about 10 JY holidays.
If you want a relaxing holiday maybe the "all inclusive" would suit better.
I would choice what appeals to you - whatever one you'll have a fab time.
Age ranges on the trips I've gone have ranged from 20's to late 70's - you don't state your age but don't let this range put you off, people mix well. Women tend to outnumber the men. Group sizes - smallest I've been on is 13 and largest 40.
Anna