The ones that I find the most useful are the 20smas on each time-frame.
Same here. 20sma or 22ema on intraday swings. Roy, the 22ema (suggested by Farley) is the only trendline I keep on my intraday Streamer charts (5, 10 or 15 min). I find that it represents S/R during trends. Less important during ranging/consolidation.
20sma is the center Bollinger Band which is very important in multiday swing trading of trending charts. Often you can trade back and forth between the 20sma and upper or lower BB piercings.