You aren't the only one struggling with GA and Excel Client, sounds like has lots of problems. We export our raw GA data using the CSV option, then build Tableau dashboards from there. Works pretty well, especially after we built a standardized master workbook, then changing out the data connection is quick and easy.
But there's even more good news on this front, here's a session at the upcoming 2012 Tableau user conference:
Maybe they'll cover some ways of better connecting to GA. Looks interesting.
The main issue is that I am we have three brands and each of these brands have seven separate websites (or more) so I need to roll all of these GA accounts together to give an overall picture but also have the data to enable me to split it out by website.
All of the tools that I have found are slow and not reliable (especially as Google as changed it authentication) I have started to look at analytics canvas but I am hoping and praying that there will be an answer in the upcoming convention in San Diego.