Titans of Twink Assemble! Raising Save DCs...

[Epametheus]

It may take some cooperation from your DM, and it will take a lot of cash, but Craft Staff + Heighten Spell might do the trick. By the current rules, only the staves from the DMG can be made, which makes the feat a waste.

A staff of Heightened Flame Strike would be good.

Otherwise, look at your spells that don't allow saves, and try to get an inherent bonus to wisdom. Save DCs don't keep up with save bonuses anymore, so past a certain point you can expect your spells to either do half or to fail outright on a consistent basis.

Wildshaping and going into melee would be your best method of dealing damage, honestly.

 

[monboesen]

Why are you relying on spells to do damage if you can turn into a friggin DRAGON?

Any way DC increasing measures have dwindled in 3.5. So besides Spell focus and Greater spell focus (and they are so not worth it with that few feats) and increasing spell casting stat theres really nothing much to do.

You will just have to accept that some (or even most) enemies will make their saves.

 

[Urbanmech]

As a high level druid don't worry so much about save DC's and focus on summoning and spells with no save. At 16th lv you can summon 1d3 Greater Earth Elementals that each will have over 200 hps and dish out some pretty good damage.

Take Empower Spell and chuck an Empowered Fire Seeds at a nonfire immune bad guy. 16d6 x 1.5 with no need to worry about SR or a save is pretty awesome. Fire Seeds is THE druid offensive spell. Flame Strike is pretty good as well since it has a 15 die cap for a 4th lv spell. I don't think there are any 3.5 wizard spells of that level that affect an area and have that high of a die cap.

Make sure you use one of those feats you have left for Natural Spell. Also Extra Wildshape from CD is pretty good since it would give you an extra use of Elemental Wildshape in a day and you could stay in Elemental form all day long. Immunity to Crits and a host of other things coupled with Fly 100 Perfect is pretty desireable.