Definitely don't underestimate the flex time. You allowing your employees to one, work from home and two, set their own hours is IMO the greatest benefit you can give them...especially if they have a family. For those of us stuck in traffic nightmares this perk is invaluable.
My boss has no problem with me working flex time, but her boss is old school and believes in "face time," so I can't take advantage of the telecommuting option as much as I would like.
As for other benefits...nothing spectacular. Actually I think they're quite craptacular. Here's my jaded outlook:
401(k) - 25% match on the first 7% of our contribution (1.75%). Used to be 3.5% until they notified us of the reduction via snail mail.
Medical - So-So, I subscribe to the "Gold Level" plan just because I participate in a number of high risk activites...skiing, hockey, horseback riding, beer pong, etc...cost me about $120 a month.
Stock Options - Ones that I have are under the strike price and they've been gradually peeling back eligibility to the sr.manager/director level, so I don't get them anymore.
Education - $4000/year for graduate level, so by May they will have paid for about $11500 of the approx $32K for my MBA. (I've learned quite a bit, but I'm skeptical if I can get the desired payback in my current company).
Insurance - One of the few bright spots. For a couple extra bucks a month my beneficiaries get 4X my salary. AD&D is also pretty good. Additional coverage for incidents that happen while travelling for work.
Vacation - I top out at 4 weeks next year (10th). Additionally get 2 floating holidays so they can accomodate various religious holidays. When your sick, we call in, still get paid.
Basically all the recent enhancements they tout to us is some stupid ass hotline where I can either talk my problems out with a counselor or tell on one of my co-workers who has offended me. We can then go to "Solutions" court.
All in all, what keeps me here is the immediate people I work with are top notch, I have a great boss (worth a lot IMO) and the basic salary is good for the Atlanta area.