Challenging.

Today these come to mind:

Ives 4
W.Schumann 4
Copland 3
Ives 2
Sessions 3
E. Carter-- Symphony for 3 Orchestras

Tempted to list Joan Tower's 'Sequoia' & 'Silver Ladders' for orchestra & Steve Reich's
'Music for 18 Musicians' too, not to mention Gershwin's orchestral music .

Ed