It would be best two have two seperate rods, one for brooks and one for tidal waters.
Like the guys say, 5 1/2' is fine, anything between 4.5' and 6 foot is ok too. If your poking through thick brush and sneaking up on spooky trout in overgrown brooks, then a longer rod is actually what you'll want so you can stay far enough back from the bank to stay hidden. 8lb test is a minumum if you plan on hooking any bigger trout (14" plus) in snaggy spots, other wise, 4lb is fine in open boulder/gravel/sandy bottom type brooks. You can't often go wrong with 8lb and if you do hook a 2lb'er, you'll have a much better chance. Nothing is more wild than a big trout in a little brook.
For tidal waters, you can land most anything that swims with a 7' med hvy action spinning outfit and a 4000 size reel and 8-12lb line, if you've got the skill and luck on your side. Otherwise, time to buy 2-3 more specialized outfits.
Spinning is best for all around fishing. You'd have to buy a much more expensive low profile baitcasting reel if you wanted to get good performance and few line tangles with a variety of lure weights. I prefer baitcasters for heavy baits and use them almost exclusively for striped bass , saltwater & musky.
I have a 7 foot and broken 7 foot @ 6, 8 ultra light that i got at cabelas with a ultra light reel and 4 spools 2 with 4 pound and 2 with 2 pound super fun with brookies and pan fish. Have caught some big bass on it but dont recommend it.............
I got myself a 5'6" Ugly Stik Lite rod from Shakespeare and paired it with a Shimamo Sienna 1000FD reel spooled with 4lb test. Great little troutin' package that i carried through the brush and hooked plenty of trout with it last year. I'm thinking of getting an ultra lite 5'6" rod/fast action and run with 2lb test and some really ultra lite tackle this season.
For tidal action there are many combo's you can run with. The important thing is to have a saltwater resistant reel!