I especially love going to Isaga late at night to eat and get a few Pilsens with friends. Many of the restaurants in Jaco close by 9 or 10.
Great ceviche (be sure to ask for tortilla chips instead of crackers), casados, arroces (rice dishes) and more.
The kitchen is always open late (usually until at least 1am) and good beer prices.
They say they've been open in Jaco since 1987 and seem to have the clientele to attest to that.
For me this is a classic Tico establishment amidst a Jaco that's been developing rapidly to cater to backpackers and ex-pat high rise condos.