I have been working with my publisher to make the slides I use for my 541 Exam certification exam prep course available as a supplement to my DB2 9 Database Administration Exam Study Guide. That material is in production now and should be available in 3 to 4 weeks. There are no plans to do any other books on the 9.7 exams - my publisher decided to wait until the DB2 10 for Linux, UNIX, and Windows exams come out before publishing any new certification exam study guides.
I would go after the DB2 9.7 DBA (541) followed by the DB2 9.7 Advanced DBA (544). That way, you would be certified at the DB2 9.7 (latest) level. The only problem with this approach is that there are no good study guides for these two exams. I am working with my publisher to make the slides I use for my 541 Certification Exam Prep training available as a book that will essentially be a supplement to my 731 book. That should be ready in 8 to 10 weeks. But there are no plans to create a study guide for the 544 exam. There is however, a study guide that I co-wrote with Dwaine Snow for the 734 exam.