Hi there. I've always liked Think Tank gear. I have the Streetwalker Harddrive Pro, which has a generous pocket for a lap top, plus plenty of space for gear. I've had several different configurations in it over the years. One was for two pro (1D/1Ds type) and one standard bodies, plus a 17-40L, 70-200L, 50mm, batteries, flash, filters, etc. Another was with my 400 DO, one pro body, as well as the 17-40, 70-200, G1xMkII, filters, batteries, etc. There definitely is plenty of room in there for your "command central" kit. Think Tank also has smaller bags that you can then use to grab a minimal amount of gear for side trips, or hanging with friends, as you say. Give them a look
https://www.thinktankphoto.com/
1DX, 1Ds MkIII IR (FSp), 1Ds MkII, 1Ds, 1D, 1V-HS, G1x II, 550D (Running ML), Elan 7e, 300D, WFT-E2A, WFT-E1A, 17-40 L, 70-200 2.8 L IS USM, 400 DO IS USM, 50 1.4, 50 1.8 Plastique Fantastique, and a host of other less-than-noteworthy detritus