I LOVED the tea at Mariage Frères but was underwhelmed by the pastries. :( Perhaps lunch is much better.

My favorite little cheap place is Nectarine on the Place des Vosges on the opposite side from Ma Bourgogne: great people-watching on the terrasse, inexpensive crêpes (about 4€?) & salads, really nice unobtrusive servers.

Jody, here's another Marais website to add to yours:
http://www.parislemarais.com

PETITE GAVROCHE
BISTROT BEAUBOURG
DAME TARTINE
LE GRIZZLI
BENOÎT
CAFÉ BEAUBOURG
TRUMILOU

I've hard good things about Au Gamin de Paris at 51 rue du Vielle du Temple.

thanks for the new "insights"