A collection of comments on vrious topics covered in this discussion. The order doesn't signify any priority; it's just working my way back up the thread.
Numbers vs Excel
The basic rule still applies: Use the software that is best for the job you want tit to do. If Excel is best for that job, then Excel is your logical choice. If Numbers is best for what you want to do, then your logical choice is Numbers. If you're like SG, you'll move back and forth between these (and other applications) depending which has the features that fit the job you're currently trying to do. All are valid strategies.
I'd like this changed in Numbers...
In these discussions, you're talking to users like yourself. Some of these users can and will tell you how you can do something with Numbers. None have the power to change the application itself. Change suggestions should be sent directly to Apple,using the Fedback channel: Numbers (menu) > Provide Numbers Fedback.
Nested sorts:
In Numbers '09 v2.x, this was done in the reorganize panel by setting a series of rules. Each rule chose the column to be sorted on, and the direction of that sort. Not stated was the fact that the sorts were actually carried out starting with the last rule in the list (just as they had been in AppleWorks, to which the iWork applications were touted as 'the successor').
In Numbers 3, the Reorganize panel is missing (so far), but the process is essentially the same. Start with the sort that would have been at the bottom of your list, and work your way to the tp of the list. Here's an example, starting with the original order:

Note that the values in column A can be used to return the table to its original order.
Desired sort:
By name, ascending.
Within the same name, by amount, ascending.
Within the same amount, by payment method, ascending.
Procedure:
Select any cell to bring the focus to the table, then:
Hover the mouse over the column D (Type) reference tab, choose Sort Ascending.
Repeat with column C (Amt)
Repeat with column B (Name)
Result:

All names are sorted in ascending order.
Within each group of the same name, payments are sorted by type.
Where there is more than one payment of th same amount, these are sorted by type (see highlighted examples).
Using an auxiliary sort column:
Because concatenation of the values in columns B, C and D produces a text string, all sorts in this column will be 'alphabetical', not numeric. To correctly sort the values in column C, these must be incorporated as text strings, padded with leading zeroes or another character that will sort before any number character to make each 'number' the same length (measured in characters). That can be done (as SGIII demonstrated) by appending an arbitrary number of zeros to the beginning of the 'number', then taking the rightmost n characters of the resulting string to use in the string being constructed for the sort.
Using an arbitrary number, though requires some skill on the part of the arbitrator. (S)he must add enough characters to accomodate the difference between the longest and the shortest 'number' in the column, and retain enough characters to accomodate the longest 'number' in the column.
SGIII wrote: "If you're doing a lot of this Barry, Jerry or others could probably give you a formula that would look for the largest number value in the column and adjust automatically."
Not all that difficult, but it does require another auxiliary column, this one to determine the length of each number, then determin the length of the longest one.
Here's the table above, with the two added columns.I've also deleted the empty (and hidden) columns in the original table, leaving only those which actually contain data.The yellow filled one shows the length in characters of each entry in column E. This column may be hidden.
Column F shows the concatenated content of columns B, C and D, with C's contents adjusted to the same length in each column. This column needs to be visible in order to be selected as the sort column for the table, but it, and/or its contents, may be reduced in size or otherwise be made less visible.

A single ascending sort on column F gives the same result as the three sorts in the example above:

Costructed and tested in Numbers '09 v2.3. All functions used are available in Numbers 3.
Regards,
Barry