I've played through the Nayuki scenario of Kanon, then played Planetarian, and recently finished Tomoyo After, which was an amazing experience for me. I wish I had played Clannad first, but I am remedying that currently. Alas, as you noted, Clannad does not feature voice unlike Tomoyo After or Kanon(through the Dreamcast voice patch). But, it seems the PS2 version of Clannad(Dec 31st release date according to Gamespy) will feature voices which can then be patched on to the PC version.

5% conversational Japanese may be right for me too, it's hard to tell, but I've been using Oh Text Hooker in combination with the Atlas translation software plugin and have been able to enjoy these games quite well. Perhaps you've heard of this? There's a great post on HF on this: http://www.hongfire.com/forum/showthread.php?t=33060

Key games tend to have video scenes where the text cannot be hooked, but I'm resolving to look up those words myself soon.

I've played through a few bishoujo games now, and IMO, Tomoyo After "It's a Wonderful Life" is the best. I love the way it uses normal everyday life(outside of school) to build a great story. Probably because I can identify with Tomoya the best of all the heros I've seen.