Major construction site. Cement mixers, girders, rebar, exposed electrical systems, piping, fencing, tools.
Abandoned prison (Alcatraz motif).
Massive hardcopy library. As rare as real books are in Shadowrun, might be interesting to have the encounter in some eccentric collector's massive library - all the care that the collector puts into keeping the books safe ... including traps ... and guards.
A zoo. Lions. Tigers. Bears. Griffons. Oh, my.
Polydamas said air or heliport.
Underwater domed building, perhaps a research laboratory or tourist attraction. "Way to go, slick, that last Panther Cannon round breached the hull and, oh, look, its the Pacific Ocean coming to play."
Junkyard. Endless maze of old crushed automobiles. Plenty of impromptu weapon options.
Arcane Runes Press has a pretty good idea: how 'bout a circus?
Hospital. Rent _Hard Boiled_ starring Chow Yun Fat, to see how a (highly stylized and coreographed, yet amazing) gun battle plays out in the place where they're supposed to stitch you back together, not blow you apart.
Fish market.
Moving train (high speed mag-lev rail - not as easy to jump off)
Condemned hotel.
Hope it goes well. Have fun.
Warrior Poet