1993 Suburban Tune-Up Questions

Here i am again with my questions. I apologize for so many posts, i just want to keep all the threads a single topic the best I can. Same 1993 Suburban, 5.7 350 engine, automatic, 4X4, 152,000 miles. I have a question about vehicle tune up. I have owned the vehicle for 1.5 years and have not tuned it up myself. I was thinking it would be a good idea to do this summer. I see tune-up kits at Checker Auto and Auto Zone for about $150. Accel High Performance Kit. Includes plugs, plug wires, plus cap and rotor.
http://www.partsamerica.com/ProductDetail.aspx?MfrCode=ACC&MfrPartNumber=TST4HP&PartType=203&PTSet=A

I was wondering if this particular kit would be a good idea, in terms of performance, and reliability. Would a kit be a good solution or would buying the items separately and different brand be better? Would more OEM style replacements be a better decision? I love my burb and i dont want to do a half arse job, which brings me to my next question. If i'm not sure a tune-up is necessary is it a good idea? I have heard premature spark plug replacement lowers fuel economy and sometimes power on newer (2000 and newer) engines. Does this apply to the good old 5.7 liter 350 TBI? I suppose theres no sense in changing something if it's not necessary, however me thinks it's possible I could be due for one soon. Thanks again so much to all those who know what they are doing and don't mind sharing!

~Suburban Freak~

Most are snake oil kits aimed at your rear pocket.
Good AC-Delco parts are the way to go.