Currently I'm level 6. I've asked for, and obtained permission, to lose my scimitar proficiency for longspear. If this wasn't the case, I'd have to switch my feats around a little:
Human Druid 6:
Feats:
1) Combat Reflexes
1) SF: Conj
3) Augment Summoning
6) Natural Spell
Mounted on the horse, I control a lot of squares with my longspear. Anything that I'm not threatening my horse is, so I'm not worried about things like that.
During early levels, I played by summoning animals and using a combination of Produce Flame for ranged attacks, as well as plowing over people with my light horse animal companion. Summoning wolves for their free trip attacks (augment at level 3 on, when I can summon 1d3), combined with Combat Reflexes, let me safely poke away at tougher opponents. Larger mobs were entangled and dealt with accordingly. Summoned animals have also helped the lone party frontman (again, by being in the way and tripping). I still have a huge move speed, though, because I can handle my horse as a free action, so even though I'm summoning I'm not stationary.
At levels 3~5, the above tactic was improved upon with Barkskin (shared) and spells such as Flaming Sphere. Being mounted lets me do things like move sphere (Move action), move (Free action to handle the horse), and attack in one round. As most characters at this level have few ways for getting in multiple attacks, simple combinations like this worked well.
At level 5, the nice mounted Flaming Sphere/Call Lightning combo comes into play, where you still can move around the field, doing 5d6 damage a round for 5 rounds with only 2 spells(although there are two reflex saves). If I ever need summons, they're a simple conversion away, too...in fact, I've used summons so much in this campaign that I actually now prefer dropping for SNA's over CXW's. I see the summons as being generally more useful: you can only heal after you've been hurt. Why bother getting hurt in the first place? Barkskin is still being used as the primary buff, as needed. Summoning multiple elementals is now also an option. If we are hurt, I usually get 2 for 1 deals with CLW.
Having my Mount be my Animal Companion is also going strong; the extra 4 HD it's picked up means that it has one of the highest HP totals in the party. Run and Endurance help me get out of a tight spot, and abilities such as Evasion and Devotion keep my mount safe.
I eventually plan on using Wildshape + Animal Growth + Share Spells to take advantage of having Huge creatures with reach. Later, I can see the mount as being used when I summon; as I will focus on being a grappling specialist with large animal forms.
