Upper Radiator Hose Pressure??

I have to agree with a lot of the posts above, and especially with AJ.

It's not a bad thermostat if it runs the temps you say it does.

A head gasket leak can cause tight hoses, and the absolute simplest way to diagnose that is with a cooling system pressure tester.
It goes on in place of your radiator cap and has a pump for building initial pressure and a gauge for watching the pressure.
The gauge on the tester will climb to a certain point and is supposed to level off at some point before it gets to hose popping pressure.
If it has a head gasket leak the pressure will steadily climb until it either blows a hose or pops the radiator or blows past the tester cap.
It really should be done by someone who knows what they are seeing on the gauge because an increase in pressure is normal, but only up to a certain point and NO more.
With a bad head gasket the pressure will spike every time the engine is revved until something gives. (hopefully the cap relief)

The fact that it hasn't exploded a hose and doesn't overheat means it is probably not a head gasket (think what 120- 140 lbs in the radiator would do)
Usually it blows coolant past the cap, aerates the coolant and THEN overheats if it's a head gasket.

Also note that in an open system (a system without a recovery type tank) the coolant is supposed to be a little below the cap opening to allow for expansion.
A closed system pushes any expanding coolant into the recovery tank and then pulls it back into the radiator when it cools down keeping the fluid always at the very top of the radiator opening. (if it's working right)

A puke tank and recovery tank are different animals.

I said I have to agree with AJ because if it's not overheating the it's probably not a head gasket leak, but just needs a lighter pressure cap to allow a little more expansion without so much pressure that it might be hard on the hoses, radiator, heater core and so on.

An actual recovery system (if it doesn't have one) would just make it that much more reliable and maintenance free as far as coolant level goes.