My moto is a little weird sometimes. Maybe once every 2 weeks it will get stuck in the obtaining IP process which results in the wifi availability not displaying in the status bar (like you described) and the wifi won't connect. If i go into system settings, into wifi, and select the network it's stuck on, it usually optains the IP and connects. Again, only happens every couple weeks but is annoying none-the-less.
Off topic but a cool wifi app, there used to be an app called auto wifi enabler, one of my favorite apps. The premise is it's an app which uses cell tower ID (not GPS polling so it doesnt waste battery) to turn the wifi radio on and off. If you connect to a wifi network, the app remembers the cell towers within range, and if you connect to those towers in the future, it turns wifi on automatically. When you leave, it turns it off. The dev removed it (dunno why) but Tasker can also do this and more if you don't mind the cost.