I started with the database design.It's not required though but helps to validate the objects structure and communication between them.I didn't modify the BDM.
For class diagram, I used defferent colors for each kinds of objects like enitity objects, utility objects, Boundary object and DAOs( people say it's not required to show DAOs , but I did and I guess it didn't harm).Initially I followed Cade's pattern then modified it.I didn't use entity beans just statless SB as facade , services and utility objects.
I put planty of comments in the class diagram to show the functionality of each object , justified the relationship between them like aggregation, composition etc.Showed the communication link to external systems.Class diagram has around 30 objects.I worked on the "program to interface" model.
There were three components diagrams and components were shown in packages to help understanding the deployment stretagy, so my component diagram is mix of component and deployment diagram.There were common packages which would be deployed in all nodes (like TOs etc).Comments
I submitted 5 sequence diagrams.There were links if the control is to be sent to other sequence diag. from one e.g link to price itinerary and pay itinerary sequence diagram from prepare itin and change itin.Comments for alternate flows and transaction.Make sure to explain the transaction.I guess this is what gave me marks in Seq. diag.Think about all the possible scenarios of transactions.Think about using a batch job for payment reversals if its needed in your design.
I submitted the assumption doc, which had links to all diargrams , assumption, design choices and other explaination. I explained briefly how the architecture satisfies non-functional and functional requements. Documents was organized in headings and bullet points ,which made is easy to comprehend I guess.
There were no major dificulties once my class diagram came in a shape.
I used : Rational XDE developed for class diagram visual paradigm for component and sequence diagram MS Word for assumption doc and generated HTML from MS Word itself to create the HTML doc for submission.
Let me know in case if you have any specific question.