Some people are quite unaware if counter height dining is a great choice for everyday use. It actually is: you won't be spending that much time seating at a table without a reason, and also, you are probably going to be a lot slimmer. In theory :)
Anyway, jokes aside, bar-height regular casual dining sets are truly great. The tables are usually located at higher level from the ground (36 inches) and chairs are made this way so they can be a perfect match for a table. Most of counter height sets accommodate 4 chair, and also most of them do come in round shape, since it's very popular for that type of furniture. Also, these types of tables along with chairs do generally take less space, since they are more 'vertical' oriented than a regular dining sets. Also, when you sit around those tables, you tend to be as close to table as possible, so for places with limited space that might be a perfect choice. Comfyco.com offers quite a good variety of bar-style dining tables and chairs.