Is there a value that I can use in a SELECT TOP that will return all rows?
Well, it looks like TOP is a BIGINT if you aren't using a PERCENT.  That means you could pass in the max value of BIGINT, 

SELECT TOP (9223372036854775807) * FROM table1


I seriously doubt you will ever see a table that large.  I'm not sure what kind of effect that would have on the query plan though.