Laptop Pro 13" or 14"??

Given how long I've kept this computer (11 years now), I would rather think long term

You have been extremely fortunate. I do not expect any computer to last longer than its' warranty period - technology moves way too fast; even if it still works, you may not be able to get to your favorite websites because they won't work with the old browser version you are using at that point. And, you will no longer get security updates which are increasingly necessary.

It really comes down to personal preference. Being that you are used to using a 17" Mac notebook, going with either a 13" or 14" model will take some getting used to ... but it shouldn't take long. Since your computing needs seem to be modest, I would suggest saving the $700 and go with the 13" model.

Regardless, you have 14 days from the purchase date to return it for a full refund should it not work out for you. Alternately, you can "hang out" at your local Apple Store to give both models a try to see what you really prefer. Just be "careful," because they have a 16" MacBook Pro model as well. ;)

You need to get a minimum of 8 GB of RAM (16 is even better) and make sure you get at least 512 GB SSD storage - 1 TB also better if you can afford it. Screen size is whatever you prefer - best to go to a store and look at both sizes.

... and just to make your choice MORE difficult, if you can tolerate the 13-in display (which has a higher resolution than your current 17-in display), choosing the MacBook Air will save you a little more money with your modest compute needs.

If you choose that model, just be sure to load it up with the same minimum features babowa called out above.