Jenica,
I havent had "better responses" from any paticular business by name perse, but I try to stick the ones I use.
My homeowners insurance agent, my car insurance agent (which are the same in my case) surely they recognize my name and every year they donate, the employees usually chip in a few bucks each too and the company sends a $50-100 check. I give them business... they support our cause.
Same with the local grocer, I walk in and talk to the manager of the store and usually they see me in there all the time (especially now with my preggo cravings and before because Mark eats so darn much). I give them the letter, hand it to them personally and ask if maybe they can talk to corporate about donating on behalf of the company, something small, and also if they could put a copy up (I include 2 letters to some businesses) in the employee break room. Maybe mention it to their employees just once at a staff meeting. If everyone who worked at the store threw in a dollar, or even 50 cents, they could have about $50-100 to give to us.
I do the same thing at the local gas station and other businesses where I frequent at least a few times a year... that way sometimes they know/remember me and I usually take the letter into those businesses personally. Sure, it does take a bit more time, but you are more likely to get some support.
Just some ideas as to how I deal with the businesses... no particular industry for us though, just businesses we frequent.