I like a good gin and tonic, but I can’t help but wonder if the tonic I use is holding me back. I usually use Schwepp’s, which is fine, but it does have a bit of a bitter aftertaste that I don’t care for. Poland Spring is awful. I’ve had G&Ts at bars where the tonic is crisp and refreshing. So, are there any widely available good tonic brands out there?
If it’s true tonic water, it’s going to have a bitter aftertaste. It’s the quinine. Just use Schweppes and add more gin. 
Well, yeah. But it’s not bitter in the best way, it’s more like a “my mouth is really dry and now I feel even thirstier, and this is not refreshing me.”
Add more lime. Or you might try Canada Dry Tonic Water. It’s available everywhere, it seems.
Yeah, I’ve gotten to the point where my gin and tonics are 70% or more gin and that seems to create that really refreshing crispness.
Both Fever Tree and Q Tonic are good. They’re pricey, though.
For really refreshing crispness, just pour chilled gin into the glass, give the bottle of tonic water a meaningful look, and drink. 
I had honestly never given the tonic water much consideration. Which is odd, considering how much I love it. I enjoy a glass of tonic water, with or without gin in it! Sometimes I have schwepps, sometimes I have grocery store brand. I can’t taste the difference between the two, personally.
You’re not drinking diet tonic, are you? I find the artificial sweeteners do bad things to my mouth. So my advice: you may as well stick with Schweppes, it’s as good as any, but make sure it’s full-fat.
Here’s my choices in order:
- Fever Tree
- Q
- Schweppes Indian Tonic (I think it’s imported from the UK)
- US Schweppes
- Canada Dry
- Everything else
Fever Tree tonic water, Boodles Gin, ice and half a lime is a sublime beverage.
(on a tangential note, Fever Tree Ginger ale is awesome with gold rum and lime as well)
I’ll second this, but without the smiley. Weak Vodka/Gin and Tonic drinks taste awful. Only one time did I order a drink and tell the bartender to make it weak since I had places to be. Never again. I’d prefer to get it made properly (which, for me, is closer to 75-90% vodka or gin) and not drink all of it.
Having said that. I prefer Schweppes.