A couple of things that come to mind:
1) for the redundant databases (data derived from operational systems) you might want to consider placing them on a simple RAID-0 set. This will give you faster loading speed than say RAID-5 and more disk space to play with. Your more important stuff, like master, msdb, and the database containing any import procedures should go on a more reliable RAID set.
2) Consider putting the OLAP database into read-only mode during the day after import has taken place. This can overcome problems with procedures and ad hoc queries that have an inappropriate isolation level.
Cheers,
- Mark