Hi everybody, this is my first post and I must thank developers for such a great player, I've used it for years now!

Since I upgraded to 1.4.5 "suggested songs" dynamic playlist doesn't behave as usual. Up to now, I could populate the playlist with songs of different styles, and the dynamic playlist would add a song for each style. You know, if here is many people, I could ask each one for a song and the result would be quite democratic 

With the current version it doesn't work like that. I can't say if it increases the list based on what (first, last, last played?), but it gets stuck in one style.

How can I tell 'suggested songs' playlist to add one song based on the last played?

This has frustrated me too. I believe our frustration lays with a change to the way play list is repopulated;
Notes:

    * Older versions of Amarok (before 1.4.5) have a noticeable delay when a track advances. Starting from 1.4.5, a pool of 200 tracks is built, and then new tracks are added from this pool - this makes the process instanteous.
    * Older versions of Amarok (before 1.4.5) had a reduced randomisation for bulk track adding (like loading a dynamic playlist, repopulating it or adding several items at once). This is much better starting from 1.4.5.
    * Older versions of Amarok (before 1.4.5) would add tracks upon track change despite there being more than "Upcoming tracks" in the playlist. Latter versions of Amarok add new tracks only when there actually are less than required tracks. - http://amarok.kde.org/wiki/Dynamic_Playlist_Walkthrough

The "problem" is that new tracks are added from a pool of 200 tracks, I believe this is too big, because by the time this pool is exhausted the playlist has all the same artists/style and thus the cycle of hearing the same artists/style instead of a mixture of styles/artists from the songs in the original playlist. This would be ok if the artists in the original playlist are related somehow but for the most part that's not the case for me.
I haven't checked yet but I hope there is a configuration option to reduce the number of tracks in the "pool" so you can get more variety.

I don't find the configuration param. I'll enter a new "wish"...