WaterWorld in Vilnius, Lithuania
Didzioji Street (opposite of Old City Hall)

Entrance fee to this strip joint is 60 Litas (Lithuanian currency is pegged to euro at 3.5~1 euro). The bar and dancing area is downstairs. There are two things that set apart this establishment from competitors in Vilnius. The first - the dancing area hosts a large glass aquarium where strip dancers (or, rather, strip swimmers :-) perform. The other difference - besides performing a variety of sophisticated strip dance routines, some of the girls inside are equally eager to provide other services.
Drinks are fairly expensive - ranging from 18 Litas for beer to some 800 Litas for average champagne.

Tipping of dancers is encouraged but not obligatory (usually 10 Litas note suffices).
Once inside and settled into comfy lounge you'll be probably approached by one of dancers that waits for her act. Girls are not aggresive, some of them speak passable English. If you are satisfied with your "unexepected" companion, she will expect a drink (a coctail that costs outrageous 40 Litas). Afterwards you have several choices:

1. Just enjoy the show and chat with a girl (budget estimate up to 200 Litas, depends on drinks and your consumption capacity)
2. Head for private room for a little of groping and fondling (so-called private dance) with the lady of your choice (budget estimate - 250 Litas for 20 minutes session).
3. Negotiate full service with her in the same private room (her fee might vary from 100 to 200 Litas, plus at least 500 Litas for "booking" the room for 40 minutes).

All in all - pretty steep. Girls' looks vary - on my rating scale (and I consider myself quite demanding) from 5 to 8 out of 10. Most are Eastern European types with good and natural bodies.

They say that Exclusive Club offers the same service in Vilnius. Not sure about this, however, I know for certain that OldTown, Sheherezada, Lu-Lu are strictly strip clubs.

Those prices are outrageous. Are there more reasonable options in Riga?

A good option is Escort service in Vilnius, but you will need patience to get it.
I have been to Vilnius and I rented a small flat for 5 nights. As soon as I was in Vilnius, I bought all the newspaper, that I could find and I looked for adds. I found some at the end of the newspaper. I can not read Lithuanian, but it's quite easy to guess. Anyway I called some of the number and it didn't work straight away, but at the end I heard a very nice English voice. What a wonderful sound she has.... I tried to explain to her, where I was living. 10 minutes later, the phone rang. She couldn't find the street. That beautiful 19 years old voice couldn't find the street, where I lived. And she didn't find it. So it was around 10 pm. I wanted to get sex right now. But I didn't know, where to go. I was just arrived and the streets, that I had seen, when I came by taxi, was really bad. I had the feeling to be in a very poor country and surely very dangerous. Well I go out. But I change my mind, because I haven't even had a map and only small streets were around me and I feel insecure.
Well some will think that I am a fearful person. The thing is that I only saw streets of Vilnius. For the rest of my trip, I realize how safe it is in this beautiful place. So I stayed at home, no sex for tonight.
The day after, I visited the place quite early and I liked it. at the beginning of the afternoon, I try to call some numbers. A man called me and said that he had some problems to find the street again. I explained to him again and then he called me that he and the escort girl were outside in the street. I go down quickly. A young guy and a beautiful young girl was there too. The guy said that he wanted to check if I really was alone. So I agree that he comes to my apartment to check that everything was ok. Then he left and I was with that marvellous 19 or 20 student of philosophy. She could speak a little bit of English. So I pay the girl about 35$ for one full hour, it was really 60 minutes. I have some photos , but how could I show them to you.