just having finished my first summer in lit at a V30-something firm (in a secondary market, where this firm is far more prominent than its NYC office), so outside the V20 but not far outside. I'll comment briefly, and transparently, on the work product: I did zero doc review, drafted briefs or large sections of the supporting briefs, and wrote many other research memos that were essentially copy pasted or incorporated into briefs ultimately written by the senior associate, on motions that went before the court during my summer. On the IP side, I did a bunch of invalidity & non-infringement claim charting analysis, which will be part of our report. So that was pretty cool. I also did a bunch of business development work that's less directly "substantive", whether on a pitch or community development. A little pro bono too.
For corporate, the "top clients at top vault firms" thing is pretty accurate. That's not what I've seen in litigation. Nearly every case I worked on was for either a household name client or a F100 that's just in a more anonymous industry. Honestly, this is because these are the only clients that can afford our rates. One of the start-ups I started the summer working on as a client wound up having to go with a boutique firm because they were defaulting on payment to the megafirm.
I will say that I found it interesting how while listed opposing counsel was almost always another large firm, the cases in SDNY or EDNY were against Cravath, Davis Polk, ect. The ones in other parts of the country had much more variety, i.e., Jenner, MoFo, Sidley, Irell, Sheppard Mullin, Quinn, whatever. This only reinforced my impression of vault as a new york phenomenon.
It looks like I'll probably be at a V10 (or V15, whatever) next summer so I can compare the experience.