Restaurants: Lady M. Cake Boutique

Lady M
UPPER EAST SIDE
41 41 East 78th Street (Between Madison Avenue and Park Avenue)
Subway: 6 to 78th Street
If you can't get into Sabarsky - or maybe even if you can - this elegant, sleek, ritzy little pastry shop is an amazing between-museums cake-and-coffee spot. Expensive, but the cakes are terrific.
SNACKS/REST STOPS; SWEETS

Restaurants: La Bonne Soupe

La Bonne Soupe
EAST MIDTOWN
48 West 55th Street between 5th and 6th avenues
Subway: F/V to 55th Street

This is the only game around here - and dead close to the MoMA - but one of my favorite spots in Manhattan for reliable, old-fashioned, affordable standards. The "soupe menu" of bread, salad, soupe, wine and dessert is heartwarming and delicious, and the fondue, croques monsieurs and other standards are all reliable and tasty, too. It's a perfect scale for eating alone and full of interesting regulars. Also a nice, gentle spot for the less adventurous or timid visitor (ie, grandparents.)