I have just answered the taxi to Son Bou question in detail on your other post. but going to Son Bou in the evening would be a drive only option as the footpath is unlit and therefore unsafe in the dark especially with a 6 year old. To be honest I personally wouldn't think it was worth the cost just for an evening out
Santo Tomas is a very quiet resort - see Top Question "is Menorca for me" on the main island forum page for info on all the resorts . Basically it has four big hotels of which only The Victoria Playa is a family hotel, there is one aparthotel specialising in the Italian market , a number of large detached villas and a couple of apartment complexes of which M&L is the largest. It is not a place buzzing with things to do in the evening in fact the Victoria Playa and the M&L entertainment complex ( called Las Dunas)are the busiest places TBH. Other than those places ,there is a small quiet bar called Bar Halley near the chemist and a bar (Nicos) by the Mestral pool area ( just across form the kids den rooms ) but other than that it is very sleepy, there are no kareoke places or the like as that is not what Santo T is about (thank goodness)
You will be offered upgrades for meal deal arrangements when you arrive and you can pay to eat in the M&L food area ( Las Dunas) but otherwise there is Restaurante Es Pins ( near the VP hotel) the Emma Hamilton, Malibou, the little cafe in the Edifcio Migorn shopping parade, Ca'n Berto, Don Tomas and Es Bruc to go to for meals out. The Hotel Santo Tomas lets non resident dine there for a fixed fee. Most places offer a kiddies menu