The copywrited title seems to be "Good Times", though it is almost universally known as "Let The Good Times Roll." This is the Grateful Dead's version from Alpine Valley in 1989: (1) the original Sam Cooke version is "I got my plans, I don't know about you" (2) the original version is "... what I'm gonna do" (3) the original is "It might be one o'clock ..." (4) the original is "Ain't felt this good ...", and "... might not feel this good again" (5) I don't know where this verse comes from. It's not in the Sam Cooke original or other covers that I know of (eg the Rolling Stones). Possibly written by the Dead themselves so as to provide a verse for each to sing?
Get in the groove and let the good times roll
We're gonna stay here till we soothe our soul
If it takes all night long
Come on and let the good times roll
We're gonna stay here till we soothe our soul
If it takes all night long
The evening sun is sinking low
The clock on the wall says it's time to go
I got plans, and I got plans for you (note 1)
I tell you exactly what we're all gonna do (note 2)
It might be twelve o'clock and it might be three (note 3)
Time doesn't mean that much to me
Ain't felt this way since I don't know when (note 4)
Might not feel this way again
It might be six o'clock and it might be eight (note 5)
It don't matter that it's getting late
We're gonna make the band play one more song
Get in the groove if it takes all night long
All night (all night)
All night (all night)
If it takes all night (all night)
You know it might take all night long (all night)
All night long (all night)
All night long (all night)
[etc]
Get in the groove and let the good times roll
We're gonna stay here till we soothe our soul
If it takes all night long