InfiniteClouds: The rejuvation spell sucks pretty bad in that it fails more than it succeeds. Right now, I have to try and secure maybe 3 successful casts in a row, save at the inn, then repeat and exit out without saving when I get screwed by 6+ fails in a row.
Is there a better way?
Murray's Isle is pretty bad since too since the decrease is negligible and you can't just pay at the travel agency and port to the springs... you MUST ride the boat...
I heard there is a fountain you can use after a boss fight somewhere... -1 year ... can you use it over and over or only once?
Rejuvenation: My general strategy is to wait until I am done playing, save, then cast Rejuvenation. If it succeeds, save and repeat; otherwise, turn off the game.
Murray's Isle is mainly useful if your aging is distributed between your party members. If you have a Divine Mace, you can trade it around so that you don't have just one character using it, and hence each trip to Murray's Isle gives you an extra 8 uses. (Alternatively, if you find the "pay to learn every spell event" and use it, I believe it allows non-casters to cast Cleric spells, provide you have a way to increase spell level (Shaman Pipe, but alignment restricted ones may raise your SL too high).)
The -1 fountain is probably usable once per trip to that dungeon, and you probably need to re-fight the boss each time. I haven't actually played that part of the game, however.
There is another way that I have found, if you don't mind exploiting a bug; age the character until she is (or is at least close to) 255 years old. Then, IIRC, a failed Rejuvenation spell can cause her age to overflow and become negative. (Note that not all aging effects have this behavior; Resurrection, for example, can't trigger age overflow.)
Note that 80 is the danger point; at 80+ years of age, the character may die when resting. At 79, I believe there's no danger of death when resting.
(Also, when getting the Enchant Item spell, I recommend leaving everybody who can't learn the spell behind, or just use NPCs and the aging fountain until you reach the "pay to learn every spell" event.)