statspack setup question

Well, I finally made the 'leap' (uh, slight hop?) from utlestat to statspack. Installed on one test database and liked what I saw. Now I need to install it on at least one (and ultimately, all) of my prod databases. A couple of questions about 'best practice'

First, any recommendations on best extent size to define for the TS that will hold the perfstat schema?

Second, it looks like we will need to set it to take snapshots at regular intervals through eight hour periods. Any recommendations on the optimum interval? Every five minutes? Thirty minutes? One hour?

As an aside, we are also investigating more sophisticated packages to assist in monitoring and tuning. Right now we are looking at BMC Patrol, Quest Spotlight, and of course OEM. Any thoughts or recommendations on any of these products? My partner went through a demo of Spotlight yesterday and is ready to buy it.

TIA

--
Ed Stevens
(Opinions expressed do not necessarily represent those of my employer.)