Good suggestion. Also adding option for "No QB/RB" should be easy and would be helpful. The rotogrinder lineup maker has that and that tool is free.
Also, not counting defense as a player from a team (or the option to enable that). When creating lineups it would be much easier to just say 0 to 1 players from every team (except for an indicated stack) and not have to worry about the defense being considered a player. When stacking sometimes you have to allow for up to 3 players from a team if you have that team's defense in your pool and then there are double stacks and stacks+RB's that you have to go though and manually exclude.