I just cut and pasted this out of the care sheets on the "pit page." They are pretty good, you should check them out if you get a chance (www.kingsnake.com/pituophis). I think that this information will answer most of your basic size/temperment questions.
1. Northern Pine: This is the longest of the Pine snake group. Animals of 7.5' are recorded, but girth is not as thick as in some of the other subspecies. Animals range in coloration to a brick red with black blotches through a yellowish background to a near perfect white animal with black blotches. Eggs are intermediate in size.
2. Southern Pine: This Pine snake is intermediate in size and girth, but is definitely the loudest hisser in captivity. Many individuals never seem to stop thrashing and hissing when held. This variety has MANY different color morphs.
3. Black Pine: These guys may be the shortest of the Pine snakes, but is definitely the thickest in diameter. They are the least likely to open-mouth strike you, but real bites are infrequent Almost all will calm down fast with proper handling. Coloration ranges from NEAR solid black (I have no concrete proof that JET BLACK adults exist) to black animals displaying brownish band or whitish verticle stripes on a black background. In general, these guys are darker the closer you get to the head. Many will keep a "white beard" at the throat.
4. Louisiana Pine: These guys are definitely the rarest of the group in captivity and in the wild. Pure animals are becoming harder and harder to find. Due to this, general characteristics describing this species is harder and harder to list. Pure specimens may be thicker that black pines AND longer than the average northern pine in captivity. Wild ones frequently are very picky feeders. Captive bred animals may only feed in secure areas and the rival the southern pines for hissing ability.
5. Bullsnakes: These guys are the most variable of all of the members in this group. Adults can range from 4' to 7 '. Feeding regime, cage sizes, etc. should vary accordingly. Excluding the northern pine, these are probably the most docile ones of the group. The number of currently available morphs rivals that of the southern pine.
Gopher Group:
1. P. c. bimaris – smallest of the three subspecies highlighted in this care guide, it also has the darkest blotch coloration. One herpetologist has postulated that this subspecies is nothing more than a color morph of P. c. vertebralis, but I'll leave that to taxonomists to debate.
2. Pacific gopher – about equal in size to the Great Basin gopher if fed the same. Wild caught Pacific gopher specimens tend to be larger than Great Basin gophers due to their habitat; P. c. catenifer is found in more agricultural regions than P. c. deserticola, which inhabits a more arid region. Color variations include both albinos and anerythristics, which produce snow Pacific gophers when combined. Pacific gophers also have a beautiful striped version that is common for this subspecies, although the blotched version is more prevalent in collections.
3. Great Basin gopher – this subspecies reaches the most northern range of any Pituophis, and, as a result, tends to be darker than most with a pattern that tends to have blotches interconnected rather than discretely separated. This subspecies has more side pattern than the Pacific gopher, although that can vary from population to population. The darker coloration, of course, is thought to lend itself to enhanced thermoregulation by allowing more heat retention during basking. This subspecies has no color morphs at this juncture although, like all gopher snakes, there is extreme variation between populations that range over such large expanses. In some of these populations the blotches are, in fact, discrete elements that are separate and distinct.