How much demolition are you planning? Are you gutting it down to the studs and joists or trying to salvage a lot of wall and floor?
Upgrade to a 2" drain line if it isn't in place already.
If at all possible, put in accessible 1/4 turn isolation valves on the supply lines.
Also, put in grab bars. Even when your heath doesn't dictate them, they are handy to have and a lot easier to put in during a reno, rather that later.
JMHO

I have actually already gutted it down to the studs, at least in the areas where the bath tub and shower were. Thanks. Those sound like good ideas on the shutoff valves, grab bar, and 2" drain.

Having installed a couple of Kohler Sterling shower/tubs a few years ago hereâÂÂs an important tip that could save you some real frustration.
Take care to assure that your walls are plumb and square also that the tub sets level. If youâÂÂre not plumb, square and level when the side walls are on you will have a gap where it meets the tub that canâÂÂt be corrected.

Thank you for the tip.

So what was your take on the Kohler Sterling line? I know the custom showers with the fancy tile and everything look nicer, etc, but we are looking for something less expensive and something that will require less maintenance. Are there any other bath/tub combos that you know of or would recommend?

I have listed some pictures of our bathroom below so you can see what we are working with.

I am looking for advice on the best way to deactivate the old bath tub drain, how to move the shower drain to line up with our new bath tub/shower combo (i.e. is there any way I can use a flexible line so I can just route from new tub to existing shower drain)? Also, once I verify I have some dead space to play with under our new tub, I was planning on cutting the lines to the old tub about 2' above the concrete and then capping them off by soldering copper caps. If I do not have to chisel out more concrete so I can cap the water lines off down below the surface of the concrete, I would rather not have to do that. Also, anytime I solder caps on lines with water in them, it is a royal pain in the tail end. Would it be okay to solder on 90 degree valves and leave them open when I am soldering them and then close them when I am finished. I know this will cost me a couple extra dollars, but I have tried this before and it is a ton easier than soldering the caps with water in the lines. I am just wondering what people's thoughts are on if they will leak in about 20 years or if I should just suck it up and do the caps.

Here is a link that might be useful: Bathroom Pictures