Query substitution variables and prompt screens; what's the better prompt screen

I have three query products on my iSeries probably like most of you.  
They are Query for AS/400, DB2 Query Manager for AS/400 and IQ by New
Generation Software, Inc.    Whoever set up the "production" queries
here has the user entering a DFU session to enter variable data.  I've
never seen such a "junk" way to allow users to enter variables.   As you
probably know, DFU us invoked via a "driver" CL program and the user can
enter data although in a most clumsy and unforgiving manner.  The
results are written to a file.  the query is run from the same CL
program and it has to be constructed such that it queries the file that
DFU wrote plus any other files from which you need data and the input to
the comparison is from the file written to by DFU.  There must be a
better way.

In my mainframe days there was QMF for querying DB2 and it was easy to
enter a substitute parm in the query and, automatically, when the user
ran the query interactively they would be prompted for variable(s) for
use in the underlying query.  No separate "DFU" required.  Do each of
the above query products work the same?  If so, how.  I have not been
able to find any good documentation that speaks to what I'm trying to
do.  

If I must write to a file because the iSeries query products don't have
as good an automatic screen prompt as mainframe QMF (and other
products), then I am thinking about using REXX to call a web browser and
display nicely formatted screens to allow the user to enter his
variables.  Then the REXX could be used like CL to invoke the query
product.

Any ideas?

Thanks in advance,

Dave Odom