Tripods
You can accomplish maximum stability for your spotting scope, or camera setup by using a heavy, wooden tripod with spiked feet, without a center column, and with a heavy head such as a ball head. But note that you might end up leaving the heavy tripod at home if you plan to move around a lot.

Gitzo have long been the choice of the professionals with its extremely sturdy aluminum tripods. They also have a large array of expensive carbon fiber versions from hand luggage size to giant sized tripods. They all have great twist leg locks, and most tripod legs are adjustable outwards for a maximum of setup positions.

Manfrotto, or Bogen as they are called in the USA are very sturdy and considerably cheaper than Gitzo. They mainly use protruding, flip lever leg locks. After extensive use these locks might fail. You should always carry with you a wrench to tighten the nuts of the bolted locks, especially if you are going on a longer trip to a sandy destination.

There are many other good tripods to investigate. But remember to check that the leg locks can be re-fastened with a wrench if it's a flip lever leg lock.

A short tripod guide can be found on: Tripod FAQ

Monopods
Monopods are very useful in good light. But in most circumstances a tripod is to be preferred. Manfrotto/Bogen 681B ($50) is a large sized aluminum monopod that is extremely sturdy. But I prefer Velbon CF-7 ($130) which is a slightly smaller Carbon Fiber pod with an ingenious antirotation twist leg lock, and a useful shoulder carrying strap. Both monopods are insulated at the top of the monopod, and the leg locks only need one hand to resize the monopod.