Personally, apart from spending time with friends I do enjoy sailing and motorboats, dancing, live concerts, flying my planes, blimp, paramotor/trike, Shergood Aviation helicopters.
In the past I have also roleplayed in various medieval fantasy, urban fantasy and sci-fi regions but that activity, while fun, always took up a bit too much of my time to leave much for other things I enjoyed.
For sailing and motorboat use, apart from doing so on my own, I like to go on cruises with groups that design routes in advance. It is a good way to get to know the grid better and see how it all fits together and it is a fun way to get to know people in the group over a shared activity.
I don't like land vehicles as much because the roads often cross through sim corners or go close to banlines and security orbs I would like to avoid.
As aggravating as it can be in SL, I love sailing. I also attend church services at UUtopia region on Thursday nights.
I love to build and create mesh avatars and clothing, make surfboards and waves, but I do that in OpenSim. We have 3500 SL sized regions that costs me less than a 5000 prim homestead.. and our surf areas are 768m or 1536m across.. so you can get up a good head of steam. :)