I think your best bet probably _is_ an (almost) full caster such as the druid. That's simply the most flexible. If you really want to have something weird, you could consider a druid/monk, who will be quite nasty in wild-shape. Since normal wild shape replaces your size, a small race is a good choice for the extra AC, and hide etc modifiers (allowing you to sneak around a little), but that means an XP penalty (which, if you're hardly levelling, makes little difference, and in any case isn't as bad as people make it out to be sometimes), or human, for the lack of XP penalty and the extra feat.
I would go druid(9)/monk(1) and take Improved Grapple as your monk bonus feat. Improved init is always nice, Natural Spell is a must, and an interesting possibility is Spell Focus(conj.)+Augment Summoning, and Extend Spell. You really want 20 Wis. If you're not playing errata, then amulets will maintain being worn while wild shaped, otherwise, that basically means 18 wis and both increases in wis. That gives you a bonus 5th level slot, and a +5 AC, willsave, and spot+listen (both quite interesting in a sneaky campaign). It's nice to have druid(8) for large wild shape, and nice to have druid(9) for the improved animal companion, and access to 5th level spells, which include the great, great
animal growth spell.
Your (say,
Riding Dog)
animal companion improves at druid level ninth, so druid (9) is a nice one to have)
A riding dog would then have 10HD, 24 AC, and 20 str, track and four other feats, and could be wearing barding, should you choose (more than enough tricks for that), giving him far more AC. His bite'll roughly be +13 (1d6+7) unless you pick something other than Weapon focus.
If you manage 20 wis, and augment summoning, then that means you can go about casting 1d3
dire wolves with a 4th level slot, and then
animal growth as a 5th level slot to grow your wolves and
animal companion - since even wild shaped your type doesn't change, it won't effect you. However, you can effect up to four animals, and it stacks with augment summoning so that means:
+12 Str, +8 Con, -2 Dex, +2 nat arm, +4 saves, DR 10/magic
This is a dire wolf with 69 hp, AC 14, DR 10/magic, bite +16 (2d6 + 19) with 10 reach, auto-trip (+21 modifier).
The best part? if you're invisible, say by the wizard, you can stay invisible.
The advantage of such a build is that you can spot/listen with the best of them (good for sneaky campaign), don't need armor (good for sneaking), and if you take your monk level not quite at first level, then you can be quite sneaky by choosing hide/move silently at those levels. You're also flexible, in that if you need to, you can be force to be reckoned with, and have access to a wide array of handy spells (such as pass without trace, longstrider, barkskin, healing), and an animal companion who has scent. You can fly.
For a sneaky campaign I'd leave con rather low and go for wis, int, con, dex, cha, str, although you might even consider dex more important (for init and skills).
