This is a homebrew class I've been working on for a while.
You give up a reaonable amount of total caster power (-2 caster levels) in return for stronger summoned creatures that are harder to banish and faster to summon, improved ability to banish other summoned creatures, and improved familiars. It isn't intended for low level characters (7th level pre-req) but is suitable for arcane and divine casters.
Grand Summoner
pre reqs
spellcraft 10, knowledge(planes):5
feats: augment summoning, spell focus:conjuration
special: know 3 "summon" spells and dismissal or banishment, speak 2 "planar" languages, no specialist wizard except conjurer.
class skills
alchemy, concentration, craft, know(planes, arcana, religion), scry, speak lang, spell craft, diplomacy, sense motive, bluff
skills 2/level
armor: none
weapons: none
spells: increase every level except @ 2, 7
bab: +1/2
saves: will good
1 specialist, familiar
2 faster summoning
3 expanded share spell
4 improved augment Summon
5 augmented familiar
6 improved banishment
7 Improved Summons
8
9 maximized summon 3/day
10 faster summoning
specialist: automatically knows all Summon spells on caster's spell list (This replaces the Conjurer specialist abilities). This adds to the number of spells the caster automatically gain. (E.G. Wizards gain 2 spells + Summon at appopriate levels)
familiar-Summoner acquires a familiar. If they already have one they acquire a second. All class levels that provide familiars stack.
faster summoning: at 2nd summon spells take 1std+1move action to cast, completing @ end of action (as compared to beginning of following turn). At 10th summon spells take 1 std action.
expanded share spell - spells shared between caster & familiar work out to 1 mile.
improved augment Summon - bonus changes to +1/2 Summoner levels
augment familiar - familiar(s) gain celestial or fiendish template (match summoner's alignment. Neutral summoners may choose their familiars' templates; may choose different templates for multiple familiars.)
Improved summon - add half Summoner levels as bonus to caster level on Summon spells. Bonus adds to difficulty for Dispel/banish/ dismissal checks on Summoned creatures. Increases summoned creatures' SR vs spells that prevent contact (e.g. Prot vs evil) and dispel/banish/dismssal spells.
improved banishment -add half Summoner levels to Dispel/ banishment checks against summoned or extraplanar creatures. Bonus also applies to defeat target creature's SR against dispel/banish.
maximize summons - as Sudden Maximize except only for Summon spells. 3/day