Tips for 4 days in Buenos Aires alone?

Hi! I'm going to be spending the Easter weekend in Buenos Aires alone (after a friend I was travelling with had to pull out of the trip) and wondered if anyone could give me some tips on fun things to do/events going on, etc? I've been to BA before (8 yrs ago) so have seen some of the tourist sites - ideas for inexpensive group activities, such as cookery/tango/spanish classes would be welcomed :) I'll keep an eye on the Internations website too! Tks :)