Regarding the

Most guys are running about 100 watts. If you run 100 watts, you should theoretically be able to work everything you hear. However, theory will only take you so far. :-) In reality, weak signals tend to get ignored in favor of strong signals, and with a low indoor antenna, your signal is going to be weaker than that of a lot of other guys running 100 watts (to 5 elements at 60 feet, for example). To make up for that fact, you need to run more power.

I've found that running about 350-400 watts will get your signal noticed, but you must be prepared to listen a lot harder and more skillfully than the other guys are listening, because most of the guys you need to hear are going to sound weaker to you than you sound to them, relatively speaking. A good part of this requires having a decently low ambient noise floor. If this is relatively low in most directions, you can take advantage of a modest power increase. Make sure you have a good receiver with adequate dynamic range to hear weaker signals in the present of stronger adjacent ones. I heartily recommend the Elecraft K3, which I have owned now for a couple of weeks. Awesome radio!

Anything in excess of 400 watts, IMO, is going to put you into Alligator Alley if you live in a typical suburban environment. You don't want to go there. Running 1.5 kW on 6 meters makes sense only when you have a *very quiet* location (typical rural or ultra-rural environment, or a contest station environment with extremely high towers to get above the noise), along with excellent receiver capabilities.

The TE Systems 0552G solid-state amp (nominal 375 watts out) is an excellent piece of equipment that puts you right in this sweet spot, but like most solid-state amplifiers, it is utterly unforgiving about input power. Driving it with a typical 100 watt rig, as I did, is inherently dangerous, because keeping the drive at 25 watts at all times is entirely up to the operator. Make a mistake that puts 100 watts into it for a second or two, and it's severely injured or dead. I know because I did this twice, and have now decided to go with good old hollow-state amplifiers. I have one on the way. :-)