Economical: providing good service or value in relation to the amount of time or money spent 经济的;实惠的
an economical car to run(= one that does not use too much petrol/gas) 节油型汽车
It would be more economical to buy the bigger size. 买尺寸大点的更实惠.

Feature: to include a particular person or thing as a special feature 以...为特色;是...的特征 VN ~ sb/sth (as sb/sth)
The film features Anthony Hopkins as Picasso. 这部电影由安东尼 霍普金斯扮演毕加索.
The latest model features alloy wheels and an electronic alarm. 最新款式的特色是合金车轮和电子报警器.
Many of the hotels featured in the brochure offer special deals for weekend breaks. 小册子列举的多家旅馆都有周末假日特别优待.

Think sth over: 仔细考虑
I'll think over your suggestion again. 我将再次仔细考虑你的建议.