Gin's Bankai is not to be underestimated in my opinion. While it is kind of boring, one thing that is to be remembered is that the farther from the hilt you go towards the point the faster it moves making it have a sort of amplication effect the farther the enemy is from the hilt. Near the end of Gin's bankai, he would be capable of doing quick slashes that cover about 50 miles a piece.
On another note Isshin's zanpakto seems to be similar to ichigo's, when he flicked it it amplified his flick and sent aizen flying through several buildings. Ichigo refers to his getsuga tensho as an "amplified swing". Bleach has got a lot of amplified attacks going on lol.