It is very hot in the Summer - July / Aug can be around 35 degrees, but usually on Menorca, there is a breeze, so you don't always feel the heat.
I've been visiting for many years. I would recommend the following, not in any particular order:
Son Bou - lovely long beach, watersports if you want, but a five minute walk up the beach and it's almost deserted (bliss), enough to do on an evening, but not too busy, pretty, got a small water park.
Arenal d'en Castell - really beautiful horseshoe beach, nice restaurants and bars , some evening entertainment. Scenic.
Santo Tomas - beach, bars, entertainment, but a fairly small resort
Punta Prima - white sand beach, a few restaurants and bars, fairly quiet.
Cala Galdana - the queen of coves apparently, very popular with lots of people but too busy for me.
Playa des Fornells a couple of km away from the gorgeous fishing town of Fornells, but has a beach, basically privately owned holiday accomodation with a few restaurants. Pretty. (Look on Owners Direct if you fancy this place)
Most of the resorts near Ciutadella don't have beaches, but are fairly busy, apart from Cala'n Bosch which has a beach and a marina, but it is a bit English, (for me) ditto Cala'n Porter.
The resorts near Mahon (Punta Prima, Binibeca are nice), but I prefer the more Menorcan towns of Es Grau and Sa Mesquida which aren't really in the UK tour
operator remit.
Good luck. I first went nearly 10 years ago, and have been back every year since.