I don't think you will find much difference between the 30-06 and the .308, ballistically they are pretty much identical except the 30-06 will handle heavier bullets better. The recoil chart in this link reflects that as well: http://www.chuckhawks.com/recoil_table.htm
Noise and muzzle blast can have a huge impact on perceived recoil. The more you quiet it down, the more pleasant it will be to shoot. Some other options to help you out are a muzzle brake, which really bumps up the noise and pretty much requires double hearing protection. A properly designed and installed muzzle brake will greatly reduce recoil though. I have a Wild West Guns Summit Lite custom rifle in 300wsm with a brake that weighs right at 5 lbs. It recoils about the same as my .223 bolt gun without a brake. You might also try a different recoil pad. Rubber pads harden as they age, plus some of the newer technology recoil pads absorb a lot more recoil than the older designs. Another option is to pick up a "Lead Sled", which uses weight to help reduce recoil.
Yes, all three cartridges use the same bullet diameter, but you can't use most bullets designed for the .308 and 30-06 in the 30-30 because they are pointed bullets. Pointed bullets in a tubular magazine are a big no-no! The pointy end lines up directly with the next primer and will set the rounds in the magazine tube off with recoil.