good cable for internal speaker wiring

Why would you not use it on tweeter? Because of skin effect? You can get smaller guage from Clairvoyant Cables.
Not that I'm recommending it over your suggestions, Stanwal.

Stanwall, did you use connectors or direct solder? If you used slide connectors, where did you get them?

There is a lot on which gauge to use on the forums; I just found that I liked smaller better. I had to use slip on because the crossover was already set up for it and it would have been very difficult to change. I found a snap on connector which makes a better contact that is made by an automobile parts manufacture for car radios; I'll try to find the box and post the part number. I got them from a local parts store but should be on the web. Cost about 5 cents each.

I used the Cardas Copper Litz wire for wiring my homemade external passive crossover to my Infinity RIIb speakers. I used 11.5 gauge on the woofers, 15.5 gauge on the EMIM mids and 17.5 gauge on the EMIT tweeters.

Litz is not the easiest to work with as every strand must be stripped of insulation, but I found that the resulting sound quality was well worth the work. Lots of details and shimmering highs. I ended up using a Demel tool with a stainless steel wire wheel, and that worked well for the stripping.

By the way, all wires were tinned then directly soldered to the drivers. Pairs of wires (+/- for each driver) were twisted together to reduce RFI pickup - the wires for the three tweeters were then bundled into one Techflex tubing bundle, as were the wires for the three mids, and the woofer wires were put into their own Techflex. Here's a picture of the install:

RSIIb Install

and here's an in-progress picture showing some of the wires bundled in Techflex and some prior to bundling.

Wiring from Crossover

.