I would definitely go for Seasons as a first choice and Free Time as a second. Bon Voyage is only interesting if you have Freetime, as if you get a nature loving sim, or even game loving sim, there's lots to do whilst on holiday. Otherwise, pre Free Time, I just found Bon Voyage lacked substance and I certainly didn't use it all that much. Seasons is excellent as it adds weather and a few new and interesting careers, as does Free Time, which gives Sims a whole lot more to do than just gain knowledge points and advance their career. They really are the best two EP's im my opinion.
Speaking of townies and the like, and being fair game ...
There was a cow mascot, you know typically annoying and troublesome, that refuses to leave Uni houses and dorms. Well ... let's just say the cow happened to be in the pool when the ladder malfunctioned. All is good. Cow now gone. But of course there's always a replacement cow, which arrives a few days later. This one, wasn't as annoying, so I just locked him out of the house and he played basketball well into the night. About which time the ghost of the dead cow made an appearance ... and scared the NEW cow to death ... so ... I have two gravestones of cow mascots, and when my sims graduated from the lot, moved in a cheerleader and llama mascot, just for good measure. *grins* It was hilarious seeing ghost cow scaring live cow. Very very funny.