Writing a paper on occasion of birthday My colleague and I intend to prepare a paper on occasion of our advisor's birthday (he turns 65 in two years). As the preparation and publishing of a math paper takes some time, I commenced planning now. We both have defended our theses.

I would appreciate any tip on this issue. For instance, the quality of journal and the number of authors. In addition, should we share our idea about such paper with advisor?
If your advisor has had a large enough impact on his field or sub-field, it may be possible to organize a special issue in honor of his birthday. For example,
Donald DeAngelis had a special issue of Ecological Modelling dedicated to him. The first article was titled "Next-generation ecological modelling: A special issue dedicated to Donald DeAngelis on the occasion of his 70th birthday". 

The entire issue may be found here and a non-paywall press released here.