I found the above 2 links to be good source for pre-trip plan. But the route I took was different, instead of traverse that they mentioned on the SE glacier and snowbowl to reach the chute (Owens/Secor), I did the traverse at the bottom and went straight up to the chute. I took the Secor chute instead of Owens since it was closer. There was snow all the way to top except for the top half of Secor chute and the last 100ft to the peak. The angle varied from 30-45 degree. Once you are above the chute on the saddle you could go up the 35degree snow slope or if you prefer talus move right to the ridge follow that to the peak. Snow was firm almost all the way.
By now the snow was getting soft so it took a lot more effort. There is snow all the way to Ritter-Banner saddle. The chute the leads to the saddle is about 50degree and with soft snow it took a lot of energy. From the saddle its about 1000ft of talus walk to the peak. Couldn't find a register on top of Banner. There was one on Ritter.
There was a group of CMC behind me on Ritter, they had done Banner the previous day. Some of them had done this before, below are some pointers from them and my observation.
1) There is a class 4 route from Ritter to Ritter-Banner saddle, it was too risky to solo. I think it would be easier to go from the saddle to the Ritter peak since you can chalk out the route. It was easier for me come down and go up again.
2) The routes described in the first link as "accidental descent route" is probably a good route up when the snow is all gone.
3) Banner peak cannot be seen from the saddle, it is behind the false peak, so while going up keep to the left of the false peak. Apprantely there is a trail with ducks leading to the peak, but I found it easier to go up straight.
4) You can come up from Thousand island lake to Ritter-Banner saddle, I believe its longer but the slope is gradual 15-20deg. There was a group which started at 5 am from that lake and were coming down from Banner talus at 3pm. They did not need crampons/ice-axe.
5) I took the shuttle $7 to Agnew meadows but it runs between 7:30-7:30 if you can get there before that you can take your vehicle to the trailhead, this way you can finish the hike in 2 days. One of the CMC guys said if you have backpacking permit then personal vehicles are allowed even during shuttle hrs. Not sure about that.
6) The CMC group did this in 2 days, first day they hiked in and did Banner. Next day morning did Ritter and hiked out in the afternoon.
Of the few peaks I have done Ritter probably had the best view from top, you can see yosemite (half dome looks real tiny), mono lake, southern sierras and a bunch of lakes.