I create my diagrams in Enterprise Architect. Sometimes I need to embed them in Power Point presentations but it does not look good in the UI as it would if I would write them there from scratch.
Is there a way to do it nicely? Which tools would you recommend to manage a long persisting architecture and also present it nicely in presentations?
EA is for making models - more functional than "pretty", so it sounds like you are using the wrong tool for the job. However, I've been in the same boat - so I know exactly what you're talking about!
Other possibilities.....
Make dedicated "pretty" diagrams where necessary, and leave the more "serious" ones for the "real" work. this might not be so viable depending on the size and complexity of the models (and the rate of change).
Get a better tool.
Give the raw diagram to someone like a designer and get them to do you a new "pretty" one.