advice on seeing other parts of England besides London in two days?

Do you mean two consecutive days in some other place, staying there the night? Bath or York are easy places to visit from London via train (pick one). My preference would be York -- town walls to walk, York Minster cathedral, the Shambles street, a nice (and free) walking tour from volunteer city hosts daily, and more. If you're going this month it might be a bit late to find accommodations though.

There's nothing wrong with spending the whole time in London.

With those two days, would that include two nights as well? Or one overnight? Personally I've really enjoyed Canterbury, and the Cathedral and St Augustine's Abbey. A comfortable place to visit for a couple days. I'm also fond of Chichester -- stayed in accommodations operated by the Chichester Cathedral and it was a perfect base for going to the Weald and Downland Museum then to Portsmouth for the Mary Rose Museum. Both are about an hour and a half train journey from London.

Whitsable, Canterbury, Rye, Eastbourne, Alfriston, East Sussex, Oxford, Cambridge, to name a few.

As an aside been visiting London for decades. Always changing, always the same. Definitely research the different neighborhoods before discounting it.

Richmond isn’t like Putney, Hammersmith isn’t like Brick Lane, Islington isn’t like Brixton.

Would your 11 year old like Mudchute Farm, riding the cable cars over Thames, street art in Shoreditch, riding a speed boat on the Thames, visiting Hamleys toy store, riding a double decker bus, horse riding in Hyde Park?

thank you for the quick replies. My thought was two days, one overnight, but could do two overnights if worth it. Right now I have 6 nights total in London.. trying to get outside of London to see something outside of city scape. thank you for your help.

for context this is my first time out of the USA! And my daughters too! So we'd like to get outside of the city for a bit.

You can also try day trips. Oxford, Cambridge or my suggestion Windsor. Easy to reach and feels very different than urban London. London has many neighborhoods outside the urban core. I spent a day visiting high gate cemetery and Hampstead heath. Had a nice dinner at Citro before returning to my hotel. You wouldn’t believe that you’re still within the confines of London.

Have a great trip!

It might help if you would take some time to see what the country offers, then come back with questions regarding areas that appeal to you - there is plenty of information to get started here on the RS website:

https://www.ricksteves.com/europe/england

A good guidebook would also aid your research:

https://store.ricksteves.com/shop/guidebooks/uk

Since it’s your first you need to research the parks of London. If you visit Richmond Park you can see fallow deer roaming. If you visit Regent Park take a paddle boat. If you visit Hyde Park take horseback ride. If you visit St James Park watch the pelicans being fed.

Countless things to see and do in the Royal Parks.

https://www.royalparks.org.uk/visit/things-see-do

Oxford or Cambridge would be a good option; one caveat is that neither has a lot of hotel choices so it may be difficult to find a good option on short notice.

If your daughter is a Harry Potter fan, then you might choose Oxford. Oxford is also pretty easy to get to from Heathrow (there is a bus called ”the airline” which departs frequently) so you could either go there directly upon arrival or you could end your trip there and take the bus to the airport to fly home.

I personally prefer Cambridge to Oxford as Cambridge seems more compact and has more of a small town feel to me. It is an hour by train from Kings Cross station.

You could also consider just taking daytrips from London. The train ride to either place is only about an hour and this saves you from having to pack up and switch hotels.

You mentioned the seaside. Brighton is easy to get to - frequent trains and a one-hour journey. As well as the (shingle) beach and the pier there is also the weird but wonderful Brighton Pavilion which is well worth a visit. Unfortunately there are no sandy beaches within such easy reach of London. There is, I seem to recall, a bit of a sandy beach at Margate.

You can also try day trips. Oxford, Cambridge or my suggestion Windsor.

That would be my suggestion. There is SO much to see in London and I would hate for you to feel shortchanged. It's also easier to do day trips than having to pack up everything and move for just one or two nights. There are plenty of places to visit that aren't too far from London. As noted above Windsor is a good possibility, but you could also do a day trip to the Cotswolds, along with Stonehenge. Here is a fairly recent post about doing the Cotswolds on a day trip from London: https://community.ricksteves.com/travel-forum/england/day-trip-to-the-cotswolds-from-london

That said, if you decide to visit Oxford, it could be done at the end of your trip. For example, 4 to 5 nights in London, then head up to Oxford, which is a fabulous city, for a night or two. Then after your visit, just take the Airline bus directly to Heathrow. It's very easy and gets you there in no time.

Kew, with its renowned gardens, is in London, but feels as though it's not. Reachable via the Tube.

Whilst there are no great sandy beaches close to London like you will find in Cornwall, Pembrokeshire or further afield there are options. Broadstairs has a couple of nice sandy beaches as well as Margate and there are also options east in Essex.

An 11 year old may love Warwick Castle in Warwick. It could be done a as daytrip or an overnight.

You have had some good answers to basically a similar question on your other thread:
https://community.ricksteves.com/travel-forum/england/question-about-a-local-tour

To refer back to your other thread, Get Your Guide has NOT been rated highly on this forum or on Trip Advisor.

About choosing other places to visit in England......Tough decision because there are so many great places, as mentioned by Claudia, VAP, and others.
MarkCW is right....a Rick Steves guidebook would help you a lot, to read about different places and choose!

Day trips from London here:
https://www.rabbies.com/en/england-tours/from-london/day-tours
Rabbies is well-regarded on this forum and has an excellent rating on Trip Advisor.
They do multi-day tours also, which you may enjoy.

The London Walks company does day trips out of London to many destinations....Oxford, Cambridge, the Cotswolds, Canterbury, Winchester, and many other locations. You meet your guide at the train station, your guide and group go together to the destination, the guide gives you a walking tour, then travels with you back to London.
Highly recommended by this forum and its members.....https://www.walks.com/

London Walks does walks around neighborhoods of London which may be interesting to you.
Plus themed walks such as a Harry Potter walk.

thank you all so much for taking the time to help me. I truly appreciate it.