Visiting Slovenia and Croatia in late April to May 15
 

I am want to book free air miles into Ljubjana,Slovenia on April 24, 2009. We will return from Dubrovnik, Croatia on May 13, 2009. We can get FREE air transportation from American Airlines if we complete the trip before May 15 for only 40,000 miles each. If we go after May 15 (possibly June 1 - 20) we will have to use 60,000 miles.
QUESTION:
How is the weather and availability of tourist towns, etc. being open that early in the season? Is this strategy just "false economy". We have 60,000 miles and CAN go in June as suggested by Rick Steves, but we don't want to bankrupt our milage account.
Quoting from Rick Steves on when to go, he says:
Mid-October thru early May are dead as a doornail. Many small coastal towns close down entirely, with only one hotel and one restaurant remaining open during the lean winter months. Anything that's open keeps very limited hours (weekday mornings only).
Have any of you travelled to Slovenia and Croatia this EARLY in the season? I don't want to go so early and then be very disappointed when I get there.Thanks for any opinions you may have. I value them all! My daughter visited this area in late May - early June 2007 and said the weather was very good, but she doesn't know about going as early as I would like.
Thanks to all Fodorites!!