If you're getting together with friends and want a nice place to hang out combined with good solid food, I'd probably put House of Soul, Gumbah's and Georgia Street Grill on the first to try list. A good combo might be to sample one these three places for lunch and then head to Liled's for a sweet treat afterward.
Many of Vallejo's restaurants tend not to be open for dinner (such as Gumbah's and Georgia Street Grill; I believe House of Soul is open for dinner.)
If you want to try some Filipino dishes, I'd start with Andrea's (1109 Maple near Springs Rd.) Also, many of the taco trucks serve up some tasty treats for relatively cheap - the two best I've found so far are Dos Hermanos (Sereno & Sonoma Blvd) and Guadalajara (Ohio & Sonoma Blvd).
Vallejo is good, as far as I can tell, for ethnic eats. What day of the week are you going and at what time?
As mentioned, House of Soul gets lots of positive mentions on the board, but I haven't been there yet.
Another soul food place is A Heavenly Taste, but from what I read, House of Soul might be the better choice.
Georgia Street Grill recently had some positive mentions. I am just not finding the more complete review using search.
One of the better places taste-wise in Vallejo is Gumbas which does mainly Italian sandwiches. It has limited hours though. It is only open for lunch Monday through Saturday.
On the waterfront is Zio Fraedo, Sardine Can and Front Room Pizza. Skip the Sardine Can. I have never had anything edible there. I keep trying but ... ick.
Front Room is the same as Front Room Pizza in San Francisco. So if you like it in SF, you will like it in Vallejo.
I went to Zio Fraedo just after they opened. It is old time Continental Cuisine. I wasn't impressed enough to return. It was ok. Here's my report with a link to the restaurant website at the end.
I had a nice, if lean brisket at Gracie's BBQ. I hear their baby back ribks are good, but no recent reports. They are closed Sundays.
Here's a report about Angelo's Italian Restaurant:
Seafood City, Valerios, 2 BBQ Joints, more
Irie Cafe got a thumbs up last year
My Homestyle Cafe is downtown, but closes early
A humble Mexican place near Marine World is Las Cuatas Mexican Restaurant
Here's a report on J&M BBQ and Parry's Pizza. Parry's has real NY style Pizza.
In the mood for pupusa's ... here's a report about Fogata and Mercy
For a cool treat on a hot day, Liled's Candy Kitchen makes their own ice cream.
There are other older reports about Filipino restaurants, but some of those restaurants come and go, so I'm not sure what is still open.
You might also consider some of the restaurants in nearby Benicia. Here's a recent thread about Benecia and Vallejo.
there has been tons of suggestions on Vallejo. The search function really works: http://www.chowhound.com/search/std?q=vallejo&board_id=1
My suggestion is House of Soul, tons of review of it too. http://www.chowhound.com/topics/show/44765?user_name=&query=vallejo