In the alt.sorcerer I am working on I took a page from Sean K. Reynolds idea of Spell Paths and slightly alterred Spell Swapping to make the Sorcerer a little more flexible and able to change those "now worthless" spell selections such as
Summon Monster I and
sleep. For more on Spell Paths you can check out Sean's website at:
http://www.seankreynolds.com/rpgfiles/misc/pathmagic.html
"Upon reaching 4th level, and at every even-numbered sorcerer level after that (6th, 8th, and so on), a sorcerer can choose to learn a new spell in place of one he already knows. In effect, the sorcerer “loses” the old spell in exchange for the new one. The new spell’s level must be the same as that of the spell being exchanged, and it must be at least two levels lower than the highest-level sorcerer spell the sorcerer can cast. A sorcerer may swap only a single spell at any given level, and must choose whether or not to swap the spell at the same time that he gains new spells known for the level.
Sorcerer spells can also grow in time and evolve into more powerful versions of old spells. This is referred to as Spell Evolution. This concept is based on the concept of spell paths (by Sean K. Reynolds), a series of spells that build and grow upon the same basic premise. When a sorcerer acquires new known spells, and they have a spell that exists on a spell path with an appropriate higher-level spell available, the sorcerer can choose to “upgrade” the spell-path spell they already know, replacing the original spell with the upgraded spell. They may then fill the abandoned spell slot with another spell that is available to them of the same spell level. A sorcerer can only upgrade one spell in this manner at any given level, even if they have multiple options for upgrading.
[Example: Vond is a Sor5 who knows the
invisibility spell. Upon reaching Sor6 he acquires a new 3rd-level spell known.
Invisibility is a 2nd-level spell on the “Path of Invisibility” and
invisibility sphere is a 3rd-level spell on that spell-path. Vond decides to upgrade his
invisibility to
invisibility sphere, which uses his new 3rd-level spell known slot. However, he now has an open spell known slot at 2nd level (formerly occupied by
invisibility), which he may use to learn any other 2nd-level spell available to him.]"