30" if you can find em, especially if any clays are on the menu. If it's entirely an open-country/clays gun I would not be at all afraid of 32" tubes. 28" is easier to find on a field gun, I would not go any shorter than this even in extremely thick brush--26" tubes are really whippy and difficult to control for most people, and the overall length of the gun is still quite short with longer barrels. Keep in mind that the length of a double gun will be similar to the length of an auto or pump with a 4" shorter barrel, but in a reasonable quality gun will have less weight out front. Best-handling gun I ever shot much was a 10lb perazzi with 34" lighter-weight fixed-choke barrels. Due to the distribution of the weight it was extremely STABLE but also exceptionally FAST handling. That's the combination I'm looking for in a shotgun, and I think more important the lighter the gun is. Assuming the barrels in whatever gun you are looking for arent super heavy the way some of the entry-level doubles are, those longer tubes really help to get that balance.