What are the opinions on bearing protectors like "Bearing Buddies?" Also, if you have bearing protectors, do you need to have your bearings re-packed and how often?  What's the best lubricant to use?

Best thing since sliced bread.   I wouldn't have a boat trailer without a self lubeing bearing cap.  I've run Bearing Buddies for many years (since they first came out), but you also need the keep the covers on them.  I changed over to a brand called Red Eye about four years ago and like them better than BB's, no where near as messy.  

You don't want to use your normal thick wheel bearing greases in them, it won't go through the outer bearing, therefore not doing anything for the inner bearing,  You pack your wheel bearings different when using them also, you want to completely fill the bearing area and the hub so when you push the outer bearing in, it pushes grease out, then put you BB on and add enough to preload the spring, and give them a shot of grease after each trip until it they get where they will maintain a small spring tension.  I usaually clean/pack mine and check the trailer brakes every spring, however I've got one trailer that hardly ever gets towed over 10 miles a trip and I've gone two without packing them.   As for the Brand name lube, I'm not picky, it's usaually a QS or Valvolin, but stay with the one you use until youi pack them again, DON'T mix greases and get two or three tubes, you will use one just packing the bearings.

Abso-friggin-lutely!!!

Best small amount of money you'll ever spend.

Maybe it's bad but my whaler trailer gets dipped in the salt weekly, I didn't dock it last year, but for the last 5 yrs (since I bought it used) I replaced bearings and never pulled of the bearing buddies ever since.  Every 4 or 5 trips, I just put the grease gun on the nipple and pump till the grease spilling out the other side changes from dirty to clean.

Vekol- one of the best products out there for for under $20 that you can put on your trailer.  Ben and LBH are giving you good advise- use the plastic caps, and a quality bearing grease.  When the old grease is pushed out by the new grease, I would just clean that off with a paper towel.

And if you do this regularly, especially at the end of your fishing season, you won't be one of those guys sitting on the side of the road.  You know, the ones you pass on the way to the lake, standing around their boat trailer  >, looking at a trailer wheel.  

Hope this further convinces you to install them-  JB

A little off the topic but on some of the trailers that I built I got a spare spindle and hub welded it to the trailer and mounter the spare to it. That way I had a complete package all ready to go in case the worse happened.

Thanks for the input guys. After the snow we're supposed to have this weekend melts off some I'm on my way to Wally World to buy a set.