I would also prefer an APPLY based solution. Using AdventureWorks:

WITH

Data AS

(

SELECT

a.*

FROM Person.Address AS a

),

StateProvince AS

(

SELECT DISTINCT

d.StateProvinceID

FROM Data AS d

)

SELECT

Selected.AddressID,

Selected.AddressLine1,

Selected.AddressLine2,

Selected.City,

Selected.StateProvinceID,

Selected.PostalCode

FROM StateProvince

CROSS APPLY

(

SELECT TOP (30) PERCENT

d2.*

FROM Data AS d2

WHERE

d2.StateProvinceID = StateProvince.StateProvinceID

ORDER BY

d2.City

) AS Selected

ORDER BY

StateProvince.StateProvinceID,

Selected.City;

This seems much clearer to me. Proper indexing might be necessary on larger input sets.