Now my dilema is the riser width. I'm looking at a 3 seat configuration of the Berkline 45004 which is 91.5" wide and wanted to build my riser at 96" wide. What do you think? Is that enough width or does it need to be wider?

96" X 76" is the size I want to build my riser. Would it work?

Edgar,

That will work just fine. Never hurts to have some overlap of a few inches per side. Will the riser be carpeted?

Yes it will be carpeted. Thanks Serge. I'll be ordering two rows of 45004 pretty soon. I'll be in contact with you.
Thanks