Since your putting up money I think you should wait to release the map list and make it set maps for the rounds... Maybe force people to play something other then the same old excrement thy play everyday.
That would make sense if the game were growing, trying to expand maps used. And in theory I like it as it forces teams to "learn" maps. But with NA/EU server switching, I don't like that idea much.
But using money or not is irrelevant to doing that. Using money increases the competitiveness and participation (im sure people are more likely to do something like book off work, or clear their schedule when theres a big prize offered). But using money, to me, seems like trying to make the tournament more intriguing to the community - so why do something that may be less intriguing because of it?
IF Bo1 I'd say: Make 5 to 7 map list, players do process of elim with team closer to top of bracket eliminating map first, final map gets played. (PROBLEM: NA vs EU server issues) -- And in this, final still Bo3
IF Bo3 I'd say: Make map pool, 7 maps, each team picks theirs and tie is done with elimination. IN THIS CASE I WOULD NOT DO DOUBLE ELIM. Double elim will make it too long. I prefer the Bo3 double elim setup - but with NA/EU it provides problems. Single elim Bo3 is likely the best option. (If you're interested in continuing tournaments in DP, maybe even cut the prize in half for this tournament, and use the other half for a tournament lets say end of Jan/Early feb. Try to have some monetary tournament every 1-2 months to keep people having a reason to play. Might work to prolong competitive scene - people seem to come back for tournaments.
That being said - adding a few less played maps is a great idea, gives "lesser" teams a higher chance by trying to go for those maps. Pforest is probably the most played map right now.