My Suggestion (July 2015)
The first thing you need is a good carry strap. I have the BlackRapid RS-7 which is great for walking/hiking. I also use a tripod and a BushHawk shoulder mount (no longer in production).
For those with heavy lenses that use a tripod 100% of the time then I would go with a Gitzo that would last a lifetime. I would also add a Gimbal head to that tripod.
But for those who wants a just as good, but cheaper setup consider a Benro C3580T Carbon Fiber tripod and for photographers a Sirui Gimbal PH-20 which has a nice resistance or fluid drag for large lenses, or for spottingscope users a Manfrotto MVH500AH Fluid Video Head. Note that for photographers the height is very individual, but in general try to get one that doesn't need the center column to be raised a lot. The Sirui Gimbal is much better than the Benro Gimbal GH2 because of its fluid motion and quick locking. For Spotting scope users this Manfrotto video head is much better than Sirui, and Benro equivalents. When it comes to the tripod you have many more options, but I have been very happy with Benro.
Another popular combo is using a shoulder mount on top of a monopod. But this requires customizations and it is up to the user to perfect this setup since I have not found any such reseller.
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. But note that you might end up
leaving the heavy tripod at home if you plan to move around a lot.
Benro and Induro are price worthy and of good quality. They are my preferred brand based on price & quality.
Gitzo have long been the choice of the professionals. They have a good reputation (long history) hence the steep prices. Gitzo 3532 LS Carbon Fiber tripod ($930) is very popular with photographers.
Manfrotto, or Bogen as they are called in the USA are very sturdy and considerably cheaper than Gitzo. They have mainly used protruding, flip lever leg locks. After extensive use these locks will 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. I started with a very affordable (cheap) Manfrotto aluminum tripod, but after too many times with leg sections that cannot be fastened I left this type and will never go back to it.
Tthere are many more good and cheap manufacturers out there. Try one out for yourself. Remember that spiked feet are great, but you would love the easy switch to rubber feet as well. You should also not select a tripod that is very heavy since you might just opt out, and not bring it along. Most important though is to get the height right. Make sure you test it with a head mounted and with your shoes on. You will be surprised that the tripod you thought to be just right is now too short. You do not want to raise the center column as it introduces camera shake (which is the reason you go with the tripod in the first place), and in most cases you want a short center column to be able to get very low to the ground when needed.
I rarely use monopods, but they are useful in offloading your shoulders when using heavy lenses. But in most circumstances a tripod is to be preferred. Manfrotto/Bogen 681B ($50) is a large sized aluminum monopod that is extremely sturdy. I own a 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.
Skimmer Ground Pod
When getting low on muddy and sandy soil then a tripod can be awkward to move about. Naturescapes Skimmer Ground Pod II($100) is the best product for this type of terrain.
This support is very useful for eliminating camera shake, and blurry pictures. I have used the now defunct BushHawk shoulder mount which had an electronic remote shutter release that was coupled to a button on the mounts pistol grip. This greatly reduced the camera shake otherwise induced by pressing the on-camera shutter release button with your finger. You could also use a quick release plate to quickly mount the bottom of the shoulder mount to a monopod. Shoulder mounts are underrepresented in bird photography, but probably because of few retailers. The majority of shoulder mount users have custom made designs or models that are no longer available..
I have since March 2011 used the shoulder strap BlackRapid RS-7. It has made it much easier walking around with the lens, not worrying about it sliding off the shoulder.
Fluid video heads (Two Way)
Manfrotto has made very good versions. It usually has a flat base fluid video head with a very smooth, adjustable movement on both axis. A Quick Release platform which is forward/backward adjustable to balance the weight better. Make sure you don't skimp on the head since the cheaper models (e.g., "mini" versions) are often shaky, or they will get hard to move when used in cold temperatures. For heavy lenses (about 2 Kg and above) you should probably look at a large head like Manfrotto MVH500AH Fluid Video Head with Flat Base which can take a payload of 5 Kg, 2.4 Kg counter balance spring, and weighs in at 0.9 Kg. Note that photographers with very large lenses usually go for a Gimbal head instead. But I personally prefer this one because of the favorable price, compact design, and smooth operation.
The latest standard for supporting super telephoto lenses on tripods,
replacing the video fluid head, is the so called Gimbal Heads. The most famous brand is the Wimberley heads. They enable amazing maneuverability for huge lenses, and have been
recommended by the best. The closest competitor is Sirui Gimbal PH-20 followed by Induro GHB2.