DR Jennifer - Finally... If you're going more for a "pot roast" type deal - a lot of gravy/sauce/drippings and vegetables - then a little bit of over-cooking won't really hurt since you'll have the gravy/sauce/drippings to moisten things back up. However, if you're going more for the London Broil type roast, well... Go to the store, and spend the $10 on a thermometer.
And if you have a cooking shop in the area - like Williams-Sonoma, etc. - give them call.
Myself, I do use a thermometer, but I've also become good at using the "touch and press" test with certain cuts of meat to determine how well-done it is. The more you cook, the more you know.

Oh, and as for searing... In a heavy(!!) skillet, heat about two tablespoons (or less if your roast has a good coating of fat on it) of oil until near smoking. Place the roast in the pan, and leave it there for at least two minute a side - usually more. When it is time to be turned, the roast should "release" itself - you do not want to end up tearing the roast. A nice brown color and crust is what you want. And, yes, it does get quite smoky, so if you have alarm issues, you can just skip it. Or also do it in the oven if you have a heavy roasting pan. But if you can sear on the stovetop, and your pan is oven safe, then you can just go ahead and place the roast and the pan in the oven after searing.
Or will be you be braising? -Which is really how a "pot roast" is "roasted" due to the addition of liquid.
Hope this didn't confuse you. It almost confused me.
Stream of consciousness cooking lessons with Jose!
