A lot of people like to go up in size, but I like to use the stock gauge, which is 18 for almost everything, with just a couple of exceptions. Keeping the gauge small will make bundling and routing a lot easier.
The cloth wire might be okay for key exposed areas, but I'd avoid it. It's too bulky, and will make routing and bundling harder.
The best source for wire is your old harness. Strip it and re-use it. This will save a lot of $.