I don't know about the pre-dreadnought.  That might be pretty tough in terms of availability.  Almost certainly going to be pretty expensive.

As far as WWI though, I've got an excellent setup I've been very happy with, in all three categories you mention.

I'm using 1/3000 scale Skytrex/Davco minis.  I've been EXTREMELY happy with them.  The problem with 1/6000 is that from "gaming distance" they just look like blobs of metal on the table. . .  IMO, you might as well use counters at this point.

You can get these ships from here:

http://www.warweb.com/skytrex-miniature … _1676.html

1/3000 is a nice combination of fairly small  to maximize your play surface, while large enough that the ships actually look like ships on the table.  Here's a couple pics of how mine turned out:

<IMG src="http://i92.photobucket.com/albums/l18/Oldmantree/Grand%20Fleets/BattleshipBusinessCard-1.jpg"></IMG>

<IMG src="http://i92.photobucket.com/albums/l18/Oldmantree/Grand%20Fleets/100_2007.jpg"></IMG>

<IMG src="http://i92.photobucket.com/albums/l18/Oldmantree/Grand%20Fleets/100_2005.jpg"></IMG>

We mounted them all on laser-cut 3"x1" bases from here:  ($9.99 for 100 bases. . . I had to order 2 bags.    )

http://www.litkoaero.com/

Printed labels on the computer. . . and play on a 3" hex mat from here:

http://www.hotzmats.com/

As you can see, the result is excellent.  We've been EXTREMELY happy with how its turned out and I can't recommend it highly enough.

One VERY important consideration, particularly if you are playing on hexes, is the size of the playing area.

While 1:3000 look nicer than 1:6000, they do mean you'll need hexes at least 2" across (and probably larger) -- considering HMS Dreadnought would come out at 2.1" (excluding base), and she was hardly the biggest ship of the era.