best place to stay near Paddington station before heading out next day

I stayed at the Delmere Hotel on Sussex Gardens, one of many on its block, a couple of blocks from the station. There's also a Hilton at the station, more expensive.

We like the modern Hotel Indigo at Paddington when we can get it with IHG points. But next time we might try this new boutique hotel. The Pilgrim.

https://thepilgrm.com

The Paddington neighborhood is loaded with hotels.
I suggest you go on Booking.com and put in London Paddington as the city. Many great places to stay will pop up.
I also often use Google Maps for rooms and click "+++" to magnify the pages. All the close hotels will pop up as little bed icons. Click on the icons to see the properties' description and customer ratings.
We usually stay around the Bayswater station which is a short taxi ride.
Note that the Heathrow Express goes in and out of the Paddington Train station that is actually separate from the close by Paddington Tube station.

We stayed at Hotel Indigo London Paddington at 16 London Street twice and enjoyed it both times. It was very convenient to walk to Paddington Station and it had a great breakfast. In the afternoon we ordered tea and scones for a treat. We also headed to Bath the next morning. Have a great time!

Corus Hyde Park Hotel -- It's a 7 minute walk to Paddington. It's directly across the street from Kensington Gardens.

There’s the Falcon Hotel. I’ve stayed there a few times and it has always met my needs.

A agree with Joel, The Falcon is a nice hotel.

The Hilton London Paddington, Praed street, has one of their entrances with access directly into the mainline station, this would very convenient for your Bath day, also the underground for other times.