I don't know for sure what LG allows, and the following suggestion is based on taking an unusual path, not the most powerful one. That said:
I've had a lot of fun giving a pally Practiced Spellcaster. At 12th you have a caster level of 6, with PS it goes up to 10th. You then have to pick spells very carefully, but for heal mount alone the extra 40 hp of healing may be worth it. Look at the durations and bonus levels (for spells that give bonuses based on caster level -- your divine favor goes from +2/+2 to +3/+3) for spells you prepare a lot.
While this won't boost your overall power level as much as some options, it does open some new options. It also means things like pearls of power (the 1st level ones are mega-cheep at 1,000 gp) become much more useful.
I've never seen anyone else do this, and I admit there are lots of tempting options that give you more overall power. I offer it up only as a way to stand out from the crowd a bit.