I don't know about the rest of you, but I have had some issues attempting to get a pipe tee to insert so that it comes off of the top or bottom of the main pipe. That is 3/4 of the connections for pipes that I deal with currently. I thought I would post on my blog the solution that I discovered and also the solution that one of my friends at Avatech shared with me.
Draw a main piece of pipe. Go to the pipe fitting button on the palette to add a pipe fitting. Find the tee that will match your system. Be sure to input the connection type and the nominal diameter that you want for your fitting. Then click on your main pipe run where you want to drop in the pipe fitting. Next type "p" for plane so you can rotate the fitting in the z direction. For my stuff I use 270 degrees to get the fitting to point up. Once your fitting is in there you can click on the "+" sign on the fitting to add piping in.
"Go ahead and place a piece of pipe. Then, when you want to come up/down with a tee instead of coming out directly with one, start the pipe tool, let your abs snap recognize where you want to connect to off the existing run, click the pipe, then go back up to your Add Pipe dialog that has probably auto-hidden and change the elevation you want to go up or down to. This will automatically insert a tee facing in the up or the down direction for you depending on the elevation specified."
I think both will work great and depending upon the situation or what you are more comfortable with they will both be applicable.