This is an easy one.  It's similar to the question that my forester colleagues get when
they give presentations: Plant Trees? Yes!! Top Trees No!!   Any other questions?
With aeration, it's about the same way. Aerate? Yes! The only real questions are how
many times per year, how deep, and how many times over the lawn.  From my standpoint,
no matter how often you aerate, it's not enough.  I suppose it's possible, but I really can't
think of a lawn that I've seen that was over-aerated.  Just so you know, here's the advice
that I give to homeowners.

It's just plain hard to grow grass in heavy clay soils.  The best think you can do to create
a more suitable growing medium is core aeration.  There are many solutions that are
offered that don't work - gypsum, sand, extra heavy watering or fertilization - so
let's look at the one that does.

You can rent an aerifier at the rental store, or hire a lawn care service to perform the
service for you.  Either way, follow these guidelines.  The overriding principle is: the more
holes the better.  Get started by watering the lawn thoroughly.  Even the best 
equipment will not penetrate dry soils.  With most equipment, one pass over the lawn
not produce satisfactory results.  So, make one pass going North-South.  The next pass
should be East-West.  If the lawn is heavily compacted, make a third pass at a
diagonal to the first two.

After all these passes, the lawn should be covered with cores.  The cores contain soil,
thatch and turf plants.  These cores should be allowed to dry for a couple of days, and
then broken up by mowing the lawn.  The broken core pieces will be spread out over the
lawn, with some particles falling back into the holes, and some over the non-cored turf
areas.  Both events will be beneficial for the lawn.

The newly opened holes will have been loosened and aerated.  Roots will now be able to
penetrate this cultivated soil much easier than before.  The non-cored areas will have a
thin layer of soil over them, which will work it's way downward over time, mixing with
the thatch layer, thereby diluting it's ill effects.  A significant portion of the lawn will now
be mostly comprised of bare soil, creating a good seedbed for over seeding.  Follow up
the aeration with the application of 1-2 pounds of bluegrass seed per 1,000sq.ft.
Irrigate lightly every day until germination, and the gradually reduce the frequency.

Aeration, as Martha Stewart says, "It's a good thing".

Roses do best with uniform soil moisture throughout the growing season.
The general rule of thumb suggests that one inch of water be applied per
week during the growing season. The amount and frequency of application
will depend on soil type.  Sandy soils will need more frequent irrigation
than heavier clay soils.  Hot temperatures would call for more frequent
irrigation, also.  The use of soaker hoses in rose beds is highly
encouraged.  Water can be delivered in adequate amounts while keeping the
foliage dry, preventing disease.
The use of mulch around roses to help retain soil moisture is a practice
that is highly encouraged.  Mulch will also help keep soils cool and help
retard weed growth.  Materials such as wood chips, straw, or dry grass
clippings make good mulches.  More decorative materials such as   shredded
hardwood bark or cocoa bean hulls could also be used.   Mulches should be
applied about two to three inches deep and replaced as  needed.  Because
organic mulches tend to bind up nitrogen as they decompose, additional
fertilizer may be needed to prevent nutrient deficiencies.
In order to maintain strong,  healthy roses, it is important to establish
an annual fertility program.  Fertilization schedules vary depending on the
types of roses being grown.  For species roses, a spring application of
general-purpose fertilizer is usually adequate for the season.
General-purpose fertilizers such as 10-10-10 or 12-12-12 are used at about
one-half to one cup per plant.  Spread the fertilizer in a band starting
six inches from the crown of the plant, going out to about 18 inches.  Work
it in lightly and water.
All other roses benefit from a second application about June 15 or at the
end of the spring bloom period.  For continuous-flowering or
repeat-blooming roses, a third application in mid-July is suggested.  No
fertilizer should be applied after August 15 so as not to encourage soft,
succulent growth that could be easily winter-damaged.  Roses can be fall
fertilized after the plants have gone dormant.  Applying fertilizer at this
time will not encourage growth but will be available as the plants start to
grow in the spring.  Also by using a fertilizer high in potassium winter
hardiness tends to be increased.
Another fertilizer option is to use a timed or controlled release
fertilizer.  These are dry, encapsulated fertilizers that release their
nutrients slowly over the season, completing their work in 4, 6, or 8
months depending on the formulation.  Nutrient release is dependent on the
soil moisture and temperature.  These materials are generally applied in
May, using about 1/2 cup per plant.  Several forms are commercially
available.