> Is it generally reliable asking Amazon support what capacity you need for a particular use case Everyone's use case is different, they are not experts at you

> Is it generally reliable asking Amazon support what capacity you need for a particular use case Everyone's use case is different, they are not experts at your application, you are. Spend some time learning about the various services, do a deep-dive and maybe even a prototype on the ones that look interesting. There are literally dozens of ways to build any application, depending on what your goals are (low cost, low latency, low maintenance, etc) > run it for a week Run it for an hour, you should be able to quickly get a cost/benefit. There are a ton of instance types, but you generally only need to test 2 or 3 families, and 2-3 sizes. (Do you need lots of RAM? CPU? Disk? FPGAs? GPUs?). It's worth the time to automate this, so you can periodically test it. (Yes, it will cost you a dollar or two.) > But what if the service is more network latency sensitive Don't forget your own part of the stack here. Writing in a scripting language can add miliseconds, as can normalizing your data (i.e. NoSQL usually prefers de-normalizing, which trades off more duplication for lower latency). You can also pay (extra) for no hypervisor.