Our current leveling plan:
Level Up->Altar->Tower->Level Up...
repeating this cycle until everything but the shop and vault are 10. We will then get the shop to 10, and finally the vault. The vault was originally in the rotation, but now that everyone's rune storage is 1 big stack of 50 xp runes and not dozens of stacks of various types and levels, no one seems to be having inventory size issues.
If anyone would prefer to see something different, please let us know.