Here is a suggestion:
Saturday May 10 - depart early (TPA-DFW-SEA) 2588 base miles
Sunday May 11 - depart VERY early (SEA-DFW-TPA) 2588 base miles + 1000 booking bonus miles - for a total of $213.20
Sunday May 11 - depart evening (TPA-DFW-SEA) 2588 base miles
Monday May 12 - arrive late (SEA-DFW-TPA) 2588 base miles + 1000 bookong bonus miles - for a total of $232.20
So, three days of flying, two nights in Seattle for a total of 10352 base miles + 2000 booking bonus miles, and if Plat or better a total of 22704 miles and 4 upgrade stickers for a price of $445.40(just under $.02 per mile). This is great for me as it puts me within a short hop of renewing my Plat status for another year. Maybe I'll go for the big one with almost 7 months left.