A lot of lovely places listed in previous replies, but one that isn't listed is Valkenburg aan de Geul, in Limburg, in the southern Netherlands - (not to be confused with Valkenburg aan Zee, a Dutch Navy base); Valkenburg has the only hilltop castle in the Netherlands, some fascinating caves, and the old town is a joy to stroll through.

Ipswich, Ben?
I was born there, but I think that it has become a bit of a dump.
It's improving especially around the Docks, but much of the picturesque centre was destroyed in the 60s.
Bury St. Edmunds is much nicer.

doonhamer, I believe today's Tour de France leg finishes at Valkenburg...you might want to catch that on Eurosports.

Ceske Krumlov, Czech Rep.

BTilke, it was Tuesday's stage, which I did manage to catch, and very nice the old place looked, too!

How about Brienz, Switzerland?
I keep going back...to apartments on the hillside with balcony overlooking pristine Lake Brienz, the surrounding snow-capped mountains, the waterfall opposite, the old dark, wooden-timbered chalets, the outdoor museum Ballenberg, the local incline steam train(Rothornbahn),the small swimming beach, the quaint restaurants and cafes with outdoor terraces overlooking the lake, the freshly caught fish, baked morning rolls and sweets, the easy accessibility to Interlaken and the jumping off points to the "high mountains"--ie: Jungfrau, etc. the small wood-carving school, the immaculate small cemetary....need I say more?

A second vote for Bayeux. It's very lovely and big enough not to be claustrophobic.

Wherever you decide to visit, have fun!

Lucca or Siena are my two favorites. Siena seems to have more tourists than Lucca but both afford a balance of small town with plenty to do including good restaurants and ease of travel to surrounding area.

I heartily agree with those who said Bath and Oxford for England. I would recommend Portmeirion, Carmarthen and Llandudno in Wales, too. If you're coming to Ireland, don't miss Kinsale, Galway or Kilkenny. Cork isn't large, though it's the second biggest city here, but it's got a fantastic small town feel to it and some lovely little nooks and crannies.

Rothenburg-ob-der-Tauber in Germany is brilliant. Aalesund, Norway is spectacular for many reasons, particular the Jugendstil Art Nouveau architecture. Also trundle through Roskilde if you're in Denmark.