For KM5 book at least 2 weeks in advance and DO NOT BE MORE THAN 15 mins late or your table is GONE GONE GONE
Dalt Villa restaurants are generally OK after August but book to get the best ones like Can Den Para, etc.
Try Pike's and Atzaro, but book a week in advance to be safe.
Same with Bambuddah Grove, its just not worth turning up blind
Villa Mercedes was rubbish last time I went but they do good very entertainments and they may now have a chef who can cook. i hope so its a nice place.
BUT some of the nicer beach places like Yumanji and Jockey Club, Blue Marlin, Kumharas are great and have entertainment on but you might like to eat earlier there, like say 8 to 10 pm. Always ask 'whats on' or find out as ther are some great nights to be had.
If you want casual and cheap Figueretas has a good strip of restaurants, but for teh best go inland to San Carlos and S Lorenzo