Just came back from Arenal D’Castell last week, I stayed at the Fiesta Castell hotel.
Around that area there are basically two directions – UP, or DOWN. Streets seem to b at a 45 degree angle and there are LOTS of steps to reach the beach. Probably not good for you.
I walk a lot – and there are some really good walks along the coast, though the terrain is a little rough in places.

However the hotel you suggest, the Aquamarina, in the corner of the bay, is actually almost on the beach, and local buses and tour buses stop right outside it.
So walking difficulties shouldn’t be an issue there.

I cannot comment about the hotel itself though and what it is like inside. I did walk past it a few times, it seems to be a very “family friendly” hotel – though actually the whole of Menorca seems that way. I’ve never seen so many baby buggies in one place as were going around the luggage carousel at the airport!

While there are regular local buses to Mahon from Arenal, there are no direct local buses to the old capital Ciutadella. One would need to change at Mercadal.
However there’s a local tour company who offer a day excursion to Ciutadella for a very reasonable 16 euros. You get 5 hours in the city, plenty of time to wander and enjoy this lovely place.

I echo what ukbill said (we were there in 2005), the Fiesta Castell Playa was a lovely hotel but it was a very steep (though short) trip back from the beach, and most of the shops/bars etc. are that end of town. (the hotel did run a minibus to the beach)

The Aguamarina is indeed well-situated for the beach though, if that is what you want, although there is not much else near it. Interestingly enough, there is no prom as such in the resort. There is a road going round the bay, but there is a row of villas backing onto the beach and you don't get a view of the beach from the road!
There are some more shops/bars at Cales Noves (sp?) slightly inland. I can't remember if that is walkable from Aguamarina if you have walking difficulties.
There is a little road train that goes round the resort.

So if you want a beach holiday then the Aguamarina will be fine (although there are flatter resorts e.g. Santo Tomas has a hotel on the beach)

If you want more bars/local atmosphere and aren't worried about a beach, then I would suggest Es Castell on the east coast. This is only a short bus ride from Mahon, and all the TOs offer trips to Cuitadella etc. Es Castell has several little harbours which are interesting, and views over the water near Mahon with lots of boats going past. You can get boat trips too. The best location would be Barcelo Hamilton (adults only) but Rey Carlos lll is also in a good location.

thankyou so much for all your help .we are off to malgrat in a few weeks and will then make our mind up about menorca.

There is a road outside the Aquamarina that goes more gently down to beach bar which then has shallower steps for access to the beach

thankyou for the information,so would the walking in that area be ok for someone with walking problems thanks

Personally, I would say not. We stayed at the Aguamarina 3 years ago and as a fit (ish) person it was a nightmare up and down to the beach everyday. We certainly kept fit that holiday thats for sure. There isnt a lot at Arenal either (although the beach is one of the best on the island) and as mentioned above, the whole resort is up and down hill wise.

For a flat resort, my recommendation would be Calan Bosch. Very flat all the way around the resort and some lovely walks around the bays and cliffs.

thanks for the information