There are a lot of choices here. Your Asacol dose is low and could be increased. Other 5-ASA's are available, as well as Sulfasalazine. The immunosuppressants (Azathioprine, 6-MP) have helped a lot of people.
In regard to Remicade and other biologicals, you can weigh the risk of possible future problems against your quality of life. Bear in mind that Remi has been in use for more than a decade now, so there is considerable information available.
Entocort, like other steroid drugs, should be limited to short-term use only. The suggestion that it isn't systemically absorbed is a myth for many of us, and we have the life-long damage to prove it. I got a very painful, progressive condition called avascular necrosis (or osteonecrosis) after taking the "safe" Entocort for an extended period. I've had two shoulder surgeries and may yet need a third, and still have pain and limited movement in the shoulder.
Your GI sounds very conservative to me. UC is an unpredictable disease that can easily get out of hand if not adequately treated, and therefore you deserve more aggressive treatment choices.
At the very least, I'd suggest a second opinion from another GI. It may also be worth a quick trip to a city to get a consult with a surgeon.
Ulcerative colitis forum co-moderator
Moderate to severe left-sided UC diagnosed 2001.
Flared for 5 years, finally in remission with Remicade since March 2006.
Avascular necrosis in both shoulders is my "forever" gift from steroids.
Colazal, Remicade, Nature's Way Primadophilus Reuteri.
"My life is an ongoing medical adventure"