Another little talked about, but really handy feature of the Battery Tender Plus is the option on charging your car's battery through the cigarette lighter socket. Both the cars here have their batteries under the back seat and topping the batteries off with that little tender is lots easier than pulling up the seat.
In addition to that trickle charger, I use a Walmart one that has 2 amp, 12 amp and instant start charging capability. I'm sure that the instant start setting is harder on the battery, but it has started vehicles with dead batteries when nothing else would.