For skills used against mobs at your level, you will have a 5% miss rate. So 5% is necessary (with fury precision talent, only 2% from gear). But d/w has a 25% miss rate for regular hits. While 1h + shield or 2h weapons have a 5% miss rate for regular damage and skills.
D/w; you will notice that when you use a skill, it has a much higher chance to crit than regular hits. Because your miss % is lowered by 20%, which increase's your crit range.
I'd go with about 5-10% base plus to hit (spec + gear), but having crit and ap are going to be more useful than to hit at a point.
If you get the addon called theory craft, it can tell you in game what a point of crit % is worth versus a point of to hit % versus 10 points of str (20 ap).
::edit::
If your tanking, having to hit is very valuable, 9% is a great number to get and keep, if you can afford to have gear with to hit in your tanking set; but don't do so if this nerfs your survivability.
So 490 defense skill + 9% to hit + ... you get the picture.
Edited, Apr 3rd 2007 11:21am by devioususer