Not sure if you've already gotten the fish yet, but a word of caution about the german blue rams... I recently was looking into getting them and asked the experts over on wetwebmedia.com about them. Turns out to do well they're VERY fussy about water parameters and even then are still very disease prone. Ideal parameters are 82-86F temp and very soft (0-3dH) and acidic (around 5.0) water. On the other hand, guppies need moderately hard and neutral water or you'll keep having them randomly drop on you. I've kept male guppies for the past year and kept having them randomly disappear for no apparent reason and it turns out that my water was extremely soft (0-2 dH) and a bit low on the pH side (6.2-6.5), which was frying them. Ideally, guppies need about 5-10dH and 6.5-8.5 pH, which is too high for the GBRs.
The temperature requirement is also pretty high for your rummy nose tetras who do best at 78F max. Keeping them at such warm temps will tend to halve their life expectancy... 82F is also at the very top end of the temp range your loaches and gourami like, so it would need to stay pretty darn near 82 the entire time for all groups to be happy.
I'd highly recommend swapping from GBRs to Bolivian Rams as they are FAR more tolerant of a wider range of temps, pH, and hardness, so it's much easier to keep them happy while housing them with the rest of your stock. You could aim for 5-10 dH, 77-78F, and 6.5-7.0 pH and keep everyone happy and disease free.