Assuming your trip is still many months away you are better off watching the airlines for sales and watching these boards. PL is great if you need to purchase a last minute ticket that would other wise cost an arm and a leg.
PL does not allow you pick your airline or travel times. The only thing you get to pick is the days of travel, and you have to agree to connect atleast once. Also they could put you on the first or last flghts of the day which may or may not work into your travel plans. For example they could put you on the 7AM departure out of MCO. You would essentially lose the last day of your vacation that way.