Rick,
Scoresheets has all types of leagues, AL only, NL only, and both. The better challenge is in the single leagues because the talent pool is smaller. I have 3 AL leagues and 3 NL leagues. You wind up drafting a total of 35 players (13 keepers and 22 regular rounds starting early March) and then you get to add two players via draft in each month of April, May, June, July, and August. If you wind up being short handed in a position due to the draft or injury you can almost always pick up what you need via trade. In fact that is the best part of Scoresheet and why it makes you really feel like a GM. If you are this experienced in fantasy baseball I truly think you will find this format better than any other you have played.