I just had some tenants move out of one of my rentals. They allowed their pets to urinate throughout the house. I've had the old carpet and pad removed, floors sealed, and new carpet & pad installed. Now it seems that the basement is infested with bedbugs. Soooo...I'm looking at $5000-6000 in repairs. 

Has anyone had success suing tenants for damages to their property? Recommendations?

Unless they are wealthy with oodles of assets hanging out there (highly unlikely), this is like squeezing blood from a stone and a waste of time.  Plus, no lawyer will take this on contingency and hourly rates will eat up your recovery.  Just a cost of doing business, unfortunately.

Small claims court at best....... as stated above, no point in throwing good money at bad....add an attorney and the loss will go up. Do small claims and you can do it yourself, have a legal judgement on their record...... and never see a dime, but at least have a legal trail follow them

IIRC under $7500 is small claims territory. 

https://www.courts.state.co.us/Forms/SubCategory.c...

You issue will be collecting the debt. Did anyone cosign? Going to small claims isn't as hard as you think. Just make sure to follow the rules.