Been there done that, just with different papers. Here is what I
have found. (This assumes you are using a windows machine and not a
Mac.)
(Note: I have a S9000, but the print engine and print heads are
identical to your S900 - the S9000 just has a wider carriage.)
1. Do a deep cleaning (again) and then recheck/readjust your head
alignment - be very critical of which bars are the most solid and
show the least stripes. Then print a Print Head Test pattern and
examine it closely and critcally - no missing segments allowed.
2. Use the High Gloss Photo Film Setting.
3. Print something with large smooth "slow" transitions of flesh
tones or sky.
(Don't worry at first about color accuracy. Make sure you can print
a picture with no micro-banding, then get the color right by
playing with paper choices and/or profiles.)
The first step (above) is to determine if your print head is bad.
If you can not get a perfect test pattern, then don't bother going
on to the next steps. Call Canon and they will send you a new print
head. Look very carefully for missing segments - any missing is
wrong. Some people report success with a couple missing segments,
but I don't buy it. The pattern should be complete with no missing
segments. (Don't know how to verify the yellow - good luck with
that and if you figure it out, let the rest of us know!)
Step 2 is reported to put down less ink than paper settings higher
on the list. I am not sure, but it does force the quality to FINE.
This slows the printer and uses more ink, but is the only way I get
printing with no micro-bands. (Note: you can set the quality to
custom on other paper types and manually set the slider to FINE.)
Step 3 gives you an unambiguous expanse to look at - something with
little or no detail so you can see the dither pattern and
micro-bands if they exist.
Note that the Canon printer uses a very regular dither pattern (not
random like some other printers.) and some people can see the
regular pattern, and will call it "micro-banding". Wrong - I have
micro-banding, micro-banding is (unfortunately) a friend of mine,
and the dither pattern is not micro-banding...

Micro-banding
appears as lines (mostly darker - in my case magenta) across the
printout in the direction of the print head movement.
If this "helps" reduce the micro-banding and the test pattern is
solid. Then the final step is to get and use a profile for the OD
paper. There are some by a regular contributer on this forum (Joe
B?). I have used his and they are good. I have since purchased
Profile Prism ($69US) and made my own profiles The results are
stunning and the microbanding is gone.
One other piece of information for you - I have both a Macintosh
and a Windows PC which I print to my S9000 with and the Mac has
almost no (virtually invisible) micro-banding, where the Windows PC
required several weeks of playing to figure out the exact settings
to get it under control.
On your photos - 5 MPixel is more than enough to print at 8x10
(unless you are a pro and sell your photos). That comment flies in
the face of MOST recommmendations here and other places. Those
recommendations are all based on getting the maximum detail you can
possibly get on a printout. The average (and even some above
average) viewers of my pictures are amazed at the "quality" of my
13 x 19 printouts from my 4Mpixel G2. Yes, if you get in real close
and know what to look for you can see the effects of the
interpolation to scale it up to that size. But, at normal viewing
distance they are very good. So, don't blame your camera or images.
They are not the problem. However, until you get everything working
right, don't do ANY editing or sharpening of the images - just
print them straight out of the camera.
So, bottom line - if you can't tame the micro-banding issue
quickly, call Canon and complain. From all the reports of
micro-banding I think they either had a bad batch of heads or have
a qualtiy control issue with these print heads. From the reports I
have read here, they will have you go through the steps above and
then if the problem persists they send out a new head which most of
the time fixes the problem. (Some people have reported having to go
through several heads to get one that worked.)
Good luck!