Years with Mets: 1978. 1996-2002 (mgr).
This one should really go without saying. But since this is a blog and I'm probably expected to write something, I'll give you three reasons Bobby V. is a Mustache Great. Here they are (in order of importance):
1. Valentine claims to have invented the wrap sandwich.
2. In 2005, Valentine won the Japan Series with the Chiba Lotte Mariners. He promptly challenged the "World Champion" Chicago White Sox to a seven game series. The challenge was not met.
3. The Mustache Incident:
"Valentine is infamous for a dubious incident during a game in 1999 in which he was discovered to have sneaked back into the team dugout after being ejected, by wearing a disguise consisting of a change of clothes, sunglasses, and a "mustache" painted on his upper lip with eye black." [Wikipedia]