If your open to suggestions might be better have a fixed inflation rate and adjust block rewards accordingly. Say you wanted to fix inflation at 2%.

((Number of coins in existence / 100) * 2) / (60 * 24 * N. days this year) /  (N. Blocks mined last minute) = Block Reward

So if you launch with 100,000 Altcoins (possibly put them in a none profit AltCoin foundation or something). The first block reward would be:

(((100000 / 100) * 2) / 525600 / 6 = 0.00063419584 Alt per block

You could also either hard code or create a formula to keep the inflation rate high the first few years (to increase coin circulation faster) and then fix itself.

year 1 inflation 20%
year 2 inflation 15%
year 3 inflation 10%
year 4 inflation 5%
year 5+ inflation 2%