Thermal bath

Yes. Weekends are especially busy, but that does not detract from the experience!
I have been to both Gellert and Szechenyi - both are wonderful!
Gellert is smaller and a little more expensive. My experience is that more local Hungarians go to Szecheney. Either are fantastico.

And they are open early to late so you can be there when it isnt so hot.

Thanks good to know.

I'm considering a visit to the baths, as they seem to be an unusual special part of Budapest. On the other hand I am a person who considers sitting in a hot tub to be like sitting in a petri dish. Is it truly worth the trouble to drag your bathing suit and towel there and sit in a pool? Do you take your valuables with you? Money? Phone? Camera? I'm having trouble visualizing this.

I was thinking about that too Linda but haven’t read anything negative about it healthwise.
I thought I read about being given a key for the locker to put your things. I was thinking of bringing a small lanyard to hold the key but I really don’t know how the key looks like as it will be my first time too. As for the phone, I might have read about picture taking not being allowed in the pool?

The key is a wristband with a computer chip in it. Hard to loose. http://szechenyispabaths.com/can-you-leave-the-bag-in-the-cabin-in-szechenyi-baths/

The thing is, the baths are not just a pool. They're part of a tradition that has been around for centuries.
For me it's an essential part of a visit to Budapest.

About the Rudas - "The bath was built in 1550, and then reconstructed by Pasha Sokoli Mustafa in 1566. Some of the Turkish-period features are still used today: the octagonal pool, the four small corner pools, each with water of a different temperature, and the characteristic Turkish dome. "

I've been to the Rudas a couple of times on women's only day (Tuesdays) and when the light shines through the openings in that dome, it is beautiful. Nothing like it here in Canada. And I've been to the Gellert on a blistering hot August day and it was so refreshing.

You can rent a towel if you don't want to bring one. Really, you just need a bathing suit and flip-flops, and depending on the pool a bathing cap, but you can buy one there. And on women's day you don't even need the bathing suit 😉

We left our things in the locker, had no problems with that, and as James pointed out the key is a plastic bracelet, the size of a watch, they fasten on securely.

Ive never been in the Rudas. Walk past a lot and seen pictures: beautiful.

At Szechenyi Baths there are vendors around the back where you can buy the souviner "Budapest" towel (or you can rent one that looks like an old handkerchief inside), flip flops (Hungarian style) and cap (which you only need in the lap pool).