• Thanks Jeff for the responses. Since its a major project I wanted to get all the input and all doubts sorted out.
    Finally on the big day, I just took a full backup and restored it ( Stopped SQL Server and made sure the network guys turned off all traffic ) . after 15 min, I started SQL Server waited for few and then confirmed  that there are no connections and finally ran FULL BACKUP of ALL databases. NO T log backups  No Diff backups. In the restore script I had to change all drive letters use MOVE OPTION and it worked like a charm,

    The destination box was also on same datacenter, so copy was faster and finally I verified that all DB's and size matched the source. The network guy said flash drives and high throughput.

    Before restoring the user databases, on destination   I transferred logins,  Along with logins the security roles for the server level princiapls ( This was missed in Dev and we had lots of issues with errors as if app login never existed  though it was ported - SERVER ROLES  need to be scripted and moved as well which no one talks about, then msdb jobs, master and msdb special objects which existed in the source ( just scripted and compared with 3rd party tool ).

    There are great scripts to generate RESTORE out there on google,  which basically get all the paths from msdb backup set and  I just used the script on the new box and restores were easy.

    Thank you again for taking the time to respond in detail. Appreciate your willigness to share your  knowledge!