One round of buffing is definately the way to go, with a possible quickened spell at the start of the 2nd round. Anything more than that, and you're going to get yourself killed waiting to get all your buffs up.
Before 9th level, the best you can pull out via SRD material is one standard-action spell. Divine Favor or Enlarge person at early levels, and Divine Power once you hit 7th. You can get Quicken on your 1st level spells as early as 9th, but given the limited number of 5th level spell slots it may be better holding off until 12th.
Quickened Divine Favor/Righteous Might is generally going to be a better combo than Quickened Enlarge Person + Divine Power, especially since you can get that enhancement bonus to Strength from items instead. Righteous Might is definately worth using in round 1.
Now, once you hit 15th level, the best round 1 buff is Quickened Divine Power + Righteous Might. Fighter BAB, +6 enhancement bonus to Strength (assuming you don't already have a Belt of Giant Strength +6), +4 size bonus to Strength, +2 size bonus to Constitution, Large size (which boosts weapon damage), a net +1 to AC (+2 natural armor, -1 size), and DR 9/evil (or good). Add in a Quickened Divine Favor (+3 luck bonus to hit and damage) for the start of round 2, and you can go through the rest of the combat without needing a single spell.
Power Attack and a two-handed weapon are nearly essential for this type of cleric, as is Quicken Spell (as mentioned above). Combat Reflexes is often overlooked, but a useful way to take advantage of your Large size when using Enlarge Person or Righteous Might. For domains, Strength is a useful choice (gives you Enlarge Person early on, and Righteous Might in a domain spell slot), and War is good choice for the free Weapon Focus and Divine Power in a spell slot (remember that the quickened version can go in the 8th level domain slot).
That's the basics. Once you start adding non-SRD stuff, the cheese adds up quick.