Samsaran spellcaster; how do you best abuse Mystic Past Life?

[Blastoguy]

Assuming I'm a wizard or cleric, what are some spells to consider taking. Starting the campaign at level 1, can expect it to last at least long enough to level up into early/mid teens, perhaps longer.

[William Ronald]

I would strongly look at any cure spells if you are an arcane caster. Take a look at different spell lists, and determine who gets certain spells the soonest. (For example, I recall that summoners get haste at 2nd level.)

[MyTThor]

Depending on if you have the opposite (divine vs arcane) caster or if you're trying to pull double duty.

If you're trying to cover both sides, Heal and Raise Dead and the restorations and break enchantments and cure spells if you're arcane.

If you're divine, then some of the blasting or utility spells off the druid list, or some of the cooler swift action spells off the paladin or inquisitor lists.

[VM mercenario]

For the wizard, take a look at the bard and the summoner. They get early level entry to a bunch of some awesome spells.
Haste at 2. Greater Dispel at 5, Heroism at 2 with greater at 5, Simulacrum at 5, Summom monster 9 at 6, bard gets some illusion, witch gets bestow curse, heal, harm and all of the inflict spells.

[Atarlost]

For the wizard:
There are some nice bard only spells. Good Hope is a nice one. Timely Inspiration is nice if you have doubts about how you'll make use of first level slots later in your career. Freedom of Movement is a good choice: What wizard doesn't want to be completely immune to grappling? Bard's Escape is a decent get out of trouble spell. Deafening Song Bold is multitarget no save no SR sonic damage with a deafness rider to make enemy casters miserable. Animate Object is the most fun looking thing on the Cleric list and while bards get rather late access to it Samsaran ex-bards don't have to wait. You might also consider Cure Light Wounds so you can use wands thereof without UMD.

The witch has Ill Omen. If you quicken it you can ensure that that roll twice happens before they have a move action to negate the spell with and that it's a saving throw against your own Save or Die. Animate Objects is available here too. Beyond that you can easily find a few otherwise divine spells, especially if yor GM lets your mystic past life have had a specific patron. There are fewer jump out and grab you choices, though.

Summoners have a lot of early entry stuff that's already on your list. If your GM lets you use mystic past life to get them early it's an option, if a bland one.

For the cleric:
Druids have a lovely spell list. Just about anything on the druid list that isn't super-circumstantial will add a lot of versatility to a cleric. The aspect of {animal} spells are generally good for battle clerics, though which one(s) is/are good depends on your build. Unless you're travel domain Longstrider is nice for offsetting the medium armor movement penalty. There are tons of blasts and battlefield control spells to appeal to a casting oriented cleric.

Inquisitor can get you See Invisible, which is kind of nice for targeting those incorporeal undead. Invisibility and Greater Invisibility are also nice.

Paladin is mostly for the litanies. I'm not impressed with this choice.

Ranger has a lot of the aspect of {animal} spells and Longstrider off the druid list and adds Gravity Bow and Lead Blades for even more battle cleric goodness. Entangle, Stone Call, and Spike Growth are low level battlefield control options the cleric otherwise lacks.