Hi Kiter girl
I am just back from kiting Costa Rica. Amazing wind in both Lake Arenal and Bahia Salinas. 20 to 30+ knots day and night for 12 days and two days of 15 knots. Rode mostly 7 and 9 meter kites. Could have gone smaller some days but did not have smaller kites with me.
Arenal was not terribly kite friendly -more of a wind surfng destination. It was gusty there and VERY windy. Nice tropical mountain setting though.
Bahia Salinas was also windy but less gusty. There scenery was very different - rocky headlands and gravel beaches. There was lots of marine life like sea turtles which were seen every ride. There were stingrays too byt they don't seem to be much of a threat if you shuffel your feet.
We stayed at Kitebordingcostarica which has a variety of lodging options ranging from dorm style to whole houses for rent. The beach is easy walking distance. I liked it but it would not likely be to the tastes of the all inclusive crowd.
I stayed both in a Cabina and the kite house. There was a very cool laid back kiting crowd there and the beach was not crowded. In fact if you started early or did a sunset ride you would likely be alone on the water.
I will go back to Salinas. I have kited in the San Blas Islands in Panama Hatteras and Shippagan as well as Ontario and rate Bahia Salinas as the best place I've been too. I cannot comment on your other options. Good luck and happy landings!