That's a really tough one! Sounds like Florence, Venice would suit boyfriend best, but they are maybe better short break destinations as you cannot really relax/ swim/ sunbathe there.
Sorrento has plenty of places of interest around, Capri, Pompeii, Amalfi, but not many art galleries/ museums. If you pick your hotel carefully you can find somewhere with lovely pool area and stunning views, which would make up for the beach being tiny and not easily accessible. Don't expect much in the way of hotel entertainment though.
What you really need is a cruise or cruise and stay, but to stay within budget you would have to book it last minute. Trust me- you would both love it!

Hi Enchanted ,been there done that on the beach/sun holiday butt the last couple of years ive discovered the alps and i am not talking sking. went to Lake Garda last year and Lake Wolfgang in Austria before that .To have sun spectular scenery and great activities to fill your day and not to mention culture ..... Mozart .s house near by day trips to Vienna,Strasburg I suggest you get the Crystal Holidays/ Lakes and Mountains brochure and have a look ps.Ilike nice food and a few drinks and these destinations have it all.

Some of this depends on whether you feel confident about driving in Italy. Tuscany is wonderful, beautiful countryside, historic hill towns and of course historic places like Florence and Pisa. Have a look in Crystal Italy brochure. We stayed in an apartment in a converted farmhouse, with a swimming pool, surounded by olive trees and vineyards, midway between Florence and Pisa. Car hire was included and essential.

If you fancy being on the coast, for a bit of sand and sea in between your sightseeing. How about the following. We did a fly drive from near Rome to south of Naples in summer 2003. We stayed for a couple of nights in this hotel in Sperlonga - a gorgeous little resort midway between Rome and Naples:

http://www.aurorahotel.it/

We actually booked direct with the hotel but a couple of tour companies use it. Your room booking also includes payment for a sunbed on their own well kept section of beach - a must in many parts of Italy.

I would also recommend the lesser known resort of Santa Maria de Castellabate, in the Cilento area, south of Naples. I know one or two of the tour companies have nice hotels there. We stayed self catering in an apartment from http://www.summerinitaly.com - from here it is possible to visit vesuvius, Pompeii, Paestum, the Amalfi coast and the lesser known and less touristy area of the Cilento.