Depends on what you want, megfitz....a quiet weekend or lively one with a bit of noise and thump....Arundel is lovely and quant...nice B&B's and great restaurants, visit the castleand its grounds, a pitch and putt , Wetlands Nature Park which is really a nice day out and on the river with birds of different species and a boat safari, lovely pubs in the area, best being The Black Rabbit which is on the river near the Wetlands Centre.
Nearby there is Swanbourne Lake with its Tea Room house and very nice walk along the lake.
Now the thump -
Butlins Bognor Regis is about 6 miles from Arundel and they have some great themed weekends all throughout the year with 60's - current music artists playing there.
Brighton is just FULL of things to do - visit the lanes, the pier, the Sea Life centre, the shops which are just great if you like to shop till you drop, great pubs, restaurants and clubs ( if you wanna let your hair down )
Nearby Worthing is great too, like Brighton but with a bit of mellow thrown in, so not so hectic. Great restaurants and pubs too and lovely hotels or Guest houses to stay at.
Above all Worthing, Brighton and Bognor Regis offer you the Sea, which is brilliant to see out of your hotel window in the morning and Arundel offers you beautiful countryside And the sea is 5 mins drive down to Littlehampton/Climping
Whatever you choose.....enjoy yourselves xxxx