Would appreciate your comments.

A base in or near Conwy makes a great deal of sense. We rented a farmhouse nearby for a week, and it was a terrific base for touring.

I spent a week in Conwy and thought it ideal. Quite a bit to see in Conwy--castle, town walls, Tudor era wealthy man's home. In the area visited Penrhyn Castle, Caernarvon Castle, Beaumaris Castle, Harlech Castle, Bodnant Gardens, Llanddudno (sp?), slate mines at Blenau Festiniog, rode on the steam railway, Bangor cathedral with its Biblical garden, Holyhead on Anglesey, some Roman ruins near Caernarvon, went up Snowdonia.

I stayed at the Castle Banke Hotel just outside the city walls. I believe it is still in business as I googled it recently for some friends.

We stayed at Bryn Guest House in Conway and loved it. http://www.bryn.org.uk/

This is probably my favorite B and B ever.

Check out my trip report. It includes info about the fanastic cottage where we stayed, as well as where we visited.

LOVED N. Wales!!!

http://www.fodors.com/community/europe/please-do-not-read-songdocs-trip-report-of-north-wales.cfm

Thank you all!! The Castlebank Hotel has one room available without a view. However, the Bryn Guesthouse has a room with a great view and I am grabbing it tonight! Sure hope that three nights is enough time to scratch the surface.

Songdoc - I am enjoying your trip report and taking notes.

Does anyone have any comments as far as dropping our rental car somewhere along the way back toward London as opposed to driving to Heathrow and then taking a cab to our hotel in South Kensington? Six of one - half dozen of the other?

By far, the easiest place to return your car is at . . . Heathrow.

And once at LHR don't even consider taking a cab - unless you are made of £££/$$$ and don't mind spending it. Either pre-book a car service or take the tube.

janisj - would you suggest a car service? Is that like our airport shuttle?

I agree that Conwy makes a good choice. It is an interesting place in its own right as well as a good gateway to Snowdonia. Be sure to visit Bodnant gardens, they are fantastic. Two steam trains in the area: the Welsh Highland Railway and the Ffestiniog Railway. Not sure how old or fit you are, but a climb up Mount Snowdon gives a fantastic sense of achievement. We walked up and got the train down - oddly easier on the legs than the other way round.
HTH
Vicky
http://postcards-pfte.blogspot.co.uk/
Celebrating the Great British Coastline

justairport.com is a good car service (sort of a private taxi). The fares are much less than a regular cab but they must be pre-booked.

The only issue - w/ a flight arrival they can monitor ETAs and adjust what time they arrive if a flight is delayed. Since you are coming in by car, you'll have to give them an arrival time. In this case I'd book over the phone instead of on-line because they'd probably pick you up at the rental return instead of a terminal.

janisj - thank you! Yes, we would definitely have to phone unless we can estimate our departure and then arrival time at the rental return, and maybe reserve for a little later time to provide for unexpected delay or something. At least, this dilemma is solved.

Thank you all for your help!

We also loved N. Wales. We stayed farther around in Criccieth because we couldn't get Conwy accommodations on short notice. Photos and comments from my blog:

http://ukfrey.blogspot.co.uk/2011/05/north-wales.html

Have fun.