Volunteering at schools/mentoring programs is a great way to feel important and kill 1-3 hours a week.
Reading can be done cheaply but doesn't provide any interaction with others.
Tennis is cheaper than golf, and more fun if you don't mind sweating out the first 10-20 thousand shots you'll miss.
Cycling is tons of fun, both moutain biking and tourning can be scenic. I prefer roud tours.
Chess is enjoyment for people of all ages, find your local club or the random guys in the park.
If you've got the cash do 2-3 things and stick with the ones you like.