You can look it up, it's in online dictionaries.

gochisou: "feast"

sama: honorific

deshita: past conjugation of "desu", meaning "is"; thus, "was"

In other words, "[that] was a feast".

Talking about being "tired", the phrase お疲れ様でした (otsukaresama deshita) is commonly used to express "thanks for the hard work" and it's a catch-all greeting for coworkers now, but it literally means something like "o tired one" and the character 疲 still means tired.

Thats just a very general thank you.