We went to the UK for a few weeks. I thought I'd put down some brief notes to perhaps help others in designing a trip. Our main source of info was Rick Steves (Britain and also the London book) with some consultation of TripAdvisor.
The main cities on our trip were London, Edinburgh, and York. The part I'll mention is the center part not really covered entirely by Rick Steves. After London and a train to York we rented a car. Then we did:
1) Travel towards Pickering with a stop for Castle Howard. I won't detail this site as you can find it online but it's very photogenic and worth a stop.
2) Overnight and then traveled to Ripon with a stop at the fantastic Rievaulx Abbey ruins. Well worth the stop plus their is a set of quaint village houses just around there -- probably expensive ones.
3) Stayed at the Old Coach Inn in Ripon for 2 nights. Great inn at a reasonable rate plus the restaurant across the street was really nice. You can have a beer and not worry about driving back.
4) Next day visited Fountains Abbey. This is a sister abbey of Rievaulx but more intact and there are large grounds to walk around with a water garden.
5) Headed to Hawes in the Yorkshire Dales. Nice town to stay the night and the local pub was authentic feeling. Lots of locals there. The Yorkshire Dales are beautiful green rolling hill farm country with streams, cows, and lots of sheep with lambs (lambing in spring).
6) Went on to Keswick in the Lake District. Rick Steves does a good job of describing this area. We stayed at the Hazeldene and it was very nice. Did a lot of hiking in the area with great views and lots of sheep, horses, and beautiful lakes.
If we went again I'd go in September rather then May. The last 4 years or so have been cooler then normal springs so don't trust the averages. When the weather goes cool off a normally cool average -- it's cold. We should have known from past experience ... oh well we still enjoyed the trip a lot.
Regarding the car rental, we used AutoEurope with a Visa credit card that included insurance. Everything on that transaction went amazingly smooth with Hertz the auto renter. I took our GPS with a Europe chip plus some backup maps. Turned out the GPS did not acquire the satellite and no GPS rental available. So we used a road atlas plus the Google directions I printed out.
DW was a bit of a car wreck by Edinburgh. I thought I was going to loose the passenger for sure. She had a bit of a problem helping with navigation as the street signage is different and often inadequate. Driving on the opposite side is not for the faint of heart. Small narrow roads and different rules of etiquette. Then there are the multi-lane roundabouts (hint: stay in the center lane until you are ready to hit your exit). We only had a few mild arguments with no knock down drag out fights.
Definitely will get a GPS setup somehow if doing this again.
Edinburgh was a nice end point. The city has fascinating architecture for me. One could spend several days there. The reason we went in May was because Edinburgh is impacted by tourists during the August festival season and somewhat into September. Then there are the midges which I understand can be pesky if you do a Highlands tour as we did (left the driving to them).
From Edinburgh we returned to London. As I mentioned the Rick Steves London book does a great job. If you have a week that would be great as we did out of towns including Windsor, Cambridge, and Hampton Court. Steves does not feature Hampton Court but we thought it was fantastic and well worth a full day, especially if you enjoy gardens along with your history -- and especially if you have seen the old Henry VIII Masterpiece series from decades ago.