Central lodging vs different stays

If you have three weeks I would absolutely recommend picking a few different bases for your trips, and taking day trips from those bases. You will waste a lot of time in transit if you don’t.

A stay in one place will certainly limit the range of places you could visit on a day trip. It depends on what kind of touring you want to do. Do you want to do a deep dive into one small particular area, or do you want to explore more of England? My preference would be to spend up go a week in one place before moving to another, knowing I still won't see everything on my list.

If you're thinking it would be nice to be flexible and decide on day trips in the morning after checking the weather, etc., that can be quite an expensive proposition when traveling by rail unless the distances are short, which some would surely not be if you opted for a single base. Long trips out and back can be pricey due to the high per-mile cost of UK rail tickets. Day-return tickets can be a comparative bargain, though; that will help.

I would be very reluctant to use London as a base for day-trips on a trip of this length, since you surely will be spending a good bit of time seeing other places. London lodging costs are very high, and you don't get a lot for your money (except proximity to London's sights, of course). I've had no trouble finding multiple convenient day-trips by rail or bus from bases in Norwich, Cambridge, Oxford, Brighton, Bristol and Chester. The Cotswolds, for example, can be visited via small-group tours from either Oxford or Bath.

I definitely recommend staying several different places with three weeks. The only central place that would make any sense would be London and you'll pay top dollar to stay in London, the train station for your day trip depending upon the direction may be the other side of town (and take 45 minutes to get to), and trains are quite expensive in England. So "day trip out of London" strategy really does not make sense. Bath and York are two obvious places you might want to choose which I have personally visited. Canterbury is a smaller city that is day trip distance from Dover (for its castle) and Rye (charming small town). You will probably want to mix it up with smaller cities and even countryside. For me renting a car for at least part of your itinerary is a good idea.

Another vote for multiple locations. No matter how you travel, a lot of time is spent returning back to the base location after a day trip. That time could be better spent seeing things. We tend to stay 2 or 3 nights at each location, but that depends on what we plan on seeing. We always have a rental car in the UK.

msshields63, your profile doesn't say where you are from, but it would be like trying to see all of California from one location. Mostly you would be seeing highways and the back end of trucks.

I agree with the recommendations to stay in different places around the country, pick 3-4 base cities and then plan day trips around those base cities.

For three weeks, yes, I’d move around. London can rip the seams off your wallet so head to other parts of the country. Newcastle or Manchester might make good bases for for exploring the northeast and northwest of England, for example.

To be clear, I love London. I spent 10 days there in 2017, 12 days there last year, and am booked for 14 days in August. But those stays were just part of long trips. Few first-time visitors to England plan to spend an entire 3-week vacation seeing London sights.

I suggest about a week in London and split the other two weeks among three or four other bases depending on your interests and how you'll be getting around. As acraven notes, three weeks is a deeper dive than most would recommend for London, especially if you haven't been elsewhere in England. But the fewer additional bases you have, the less time you'll spend packing, unpacking, checking in and out of hotels, etc. Short-distance day trips can be easy and worthwhile, long-distance ones can be tedious and expensive.

We spent three weeks in 2016 and moved around -- staying in each place for 2-3 days, ending in Horsham (near Gatwick), where we turned in the car and got around on foot for the remaining two days. We saw a LOT and our next visit will be more of staying in each place for weeks. Getting around is somewhat different from the US.

Staying inside the M25 will make you spend some time in traffic (then there's the congestion charge if you have to drive the M25). Daytrip distance from any of the cities will depend on each location (origin and destination). The motorways aren't quite as ubiquitous as they are in the US, either, and then there's the speed cameras, so distances covered could be shorter in a day's reach. Aside from the motorways, the A-roads are usually decently fast (about the same as a state highway). The B-roads can be quite narrow and you'll drive much more slowly on them (some of them are barely more than a car-width wide!). SatNav from Waze was usually fairly accurate with respect to ETA's

We very much enjoyed travelling around and recommend it! Once you get used to the gearshift on your left, it all falls into place :-)