Expect some minor surprises, but the Big Two in Spain should make it through.
Bayern Munich and Real Madrid square off first at the Allianz Arena, a stadium all four semi-finalists will want to be at in just over month. Madrid looks stronger to me based from their form in both La Liga and in the Champions League. Bayern seem to have conceded the Bundesliga title to Borussia Dortmund, and for me run hot and cold in the Champions League. They lost 0-1 against Basel in the Round of Sixteen, before destroying them 7-0 at home. That the final is in Munich in late May is a red herring. Pros are pros, and Madrid's are just better than Bayern's.
In the other semifinal, Barcelona look stronger than Chelsea, but there is good reason for Barcelona to be very weary of the Blues. To me Chelsea appear as a wounded dog, possibly with rabies, that may or may not lash out at you and dish you a fatal blow. The Blues' upcoming fixtures look really exhausting to me (at Wembley against Spurs in an FA Cup Semifinal, home v. Barcelona; away to Arsenal; away to Barcelona). Expect at least one loss from those four fixtures, hopefully one big one against Barcelona.
See you at the Camp Nou!