Jazz fest is 10 days, the last weekend in April and the first weekend in May. and the days in between. There are scheduled events both weekends and the mid week Thursday. Which weekend is better depends on the schedule. If there is a must see group (for you) you need to be there on the day they play. The problem is that they havent yet posted next years schedule, but its already time to book your room....You could of course book all 10 days, and sublet the weekend you dont use.
You will probably have trouble finding an exchange into a New Orleans Timeshare for Jazz Fest. The fixed weeks owners will usually use what they own themselves or rent it. However Wyndham points owners can start making reservations at Avenue Plaza or La Belle Maison next week (10 months out) so for timeshares Id advise finding a Wyndham owner and making a private exchange...but do it soon; these weekends will fill up fast. Bluegreen is also a possibility, they have some points inventory at Club La Pension
as far as a hotel stay in one of the properties on or near Canal St in the central business district..There is good public transportation to the fairgrounds from there